LambdaHack

A game engine library for tactical squad ASCII roguelike dungeon crawlers https://lambdahack.github.io

Version on this page:0.8.3.0
LTS Haskell 12.19:0.8.3.0
Stackage Nightly 2018-09-28:0.8.3.0
Latest on Hackage:0.8.3.0

See all snapshots LambdaHack appears in

BSD3 licensed by Andres Loeh, Mikolaj Konarski
Maintained by Mikolaj Konarski

Module documentation for 0.8.3.0

LambdaHack

Build Status Hackage Join the chat at https://gitter.im/LambdaHack/LambdaHack

LambdaHack is a Haskell1 game engine library for ASCII roguelike2 games of arbitrary theme, size and complexity, with optional tactical squad combat. It’s packaged together with a sample dungeon crawler in fantasy setting that can be tried out in the browser at http://lambdahack.github.io. (It runs fastest on Chrome. Keyboard commands and savefiles are supported only on recent enough versions of browsers. Mouse should work everywhere.)

As an example of the engine’s capabilities, here is a showcase of shooting down explosive projectiles. A couple were shot down close enough to enemies to harm them. Others exploded closer to our party members and took out of the air the projectiles that would otherwise harm them.

gameplay screenshot

This was a semi-automatic stealthy speedrun of the escape scenario of the sample game that comes with the engine. Small fixed font. The enemy gang has a huge numerical and equipment superiority. Our team loots the area on auto-pilot until the first foe is spotted. Then they scout out enemy positions. Then hero 1 draws enemies and unfortunately enemy fire as well, which is when he valiantly shoots down explosives to avoid the worst damage. Then heroine 2 sneaks behind enemy lines to reach the remaining treasure. That accomplished, the captain signals retreat and leaves for the next area (the zoo).

Using the engine

To use the engine, you need to specify the content to be procedurally generated. You specify what the game world is made of (entities, their relations, physics and lore) and the engine builds the world and runs it. The library lets you compile a ready-to-play game binary, using either the supplied or a custom-made main loop. Several frontends are available (SDL2 is the default for desktop and there is a JavaScript browser frontend) and many other generic engine components are easily overridden, but the fundamental source of flexibility lies in the strict and type-safe separation of code from the content and of clients (human and AI-controlled) from the server.

Please see the changelog file for recent improvements and the issue tracker for short-term plans. Long term goals include multiplayer tactical squad combat, in-game content creation, auto-balancing and persistent content modification based on player behaviour. Contributions are welcome.

Other games known to use the LambdaHack library:

  • Allure of the Stars6, a near-future Sci-Fi game
  • Space Privateers8, an adventure game set in far future

Note: the engine and the example game are bundled together in a single Hackage3 package released under the permissive BSD3 license. You are welcome to create your own games by forking and modifying the single package, but please consider eventually splitting your changes into a separate content-only package that depends on the upstream engine library. This will help us exchange ideas and share improvements to the common codebase. Alternatively, you can already start the development in separation by cloning and rewriting Allure of the Stars10 and mix and merge with the example LambdaHack game rules at will. Note that the LambdaHack sample game derives from the Hack/Nethack visual and narrative tradition9, while Allure of the Stars uses the more free-form Moria/Angband style (it also uses the AGPL license, and BSD3 + AGPL = AGPL, so make sure you want to liberate your code and content to such an extent).

When creating a new game based on LambdaHack I’ve found it useful to place completely new content at the end of the content files to distinguish from merely modified original LambdaHack content and thus help merging with new releases. Removals of LambdaHack content merge reasonably well, so there are no special considerations. When modifying individual content items, it makes sense to keep their Haskell identifier names and change only in-game names and possibly frequency group names.

Installation of the sample game from binary archives

The game runs rather slowly in the browser (fastest on Chrome) and you are limited to only one font, though it’s scalable. Also, savefiles are prone to corruption on the browser, e.g., when it’s closed while the game is still saving progress (which takes a long time). Hence, after trying out the game, you may prefer to use a native binary for your architecture, if it exists.

Pre-compiled game binaries are available through the release page11 (and, for Windows, continuously from AppVeyor18). To use a pre-compiled binary archive, unpack it and run the executable in the unpacked directory or use program shortcuts from the installer, if available.

On Linux, make sure you have the SDL2 libraries installed on your system (e.g., libsdl2-2.0-0, libsdl2-ttf-2.0-0 on Ubuntu). On Mac OS X, you need SDL2 installed, e.g., from libsdlorg. For Windows, the SDL2 and all other needed libraries are already contained in the game’s binary archive. Note that Windows binaries no longer work on Windows XP, since Cygwin and MSYS2 dropped support for XP.

Screen and keyboard configuration

The game UI can be configured via a config file. The default settings, the same that are built into the binary, are in GameDefinition/config.ui.default. When the game is run for the first time, the file is copied to the default user data folder, which is ~/.LambdaHack/ on Linux, C:\Users\<username>\AppData\Roaming\LambdaHack\ (or C:\Documents And Settings\user\Application Data\LambdaHack\ or something else altogether) on Windows, and in RMB menu, under Inspect/Application/Local Storage when run inside the Chrome browser.

Screen font can be changed by editing the config file in the user data folder. For a small game window, the highly optimized 16x16x.fon and 8x8x.fon bitmap fonts are the best, but for larger window sizes or if you require international characters (e.g. to give custom names to player characters), a modern scalable font supplied with the game is the only option. The game window automatically scales according to the specified font size.

If you don’t have a numeric keypad, you can use mouse or laptop keys (uk8o79jl) for movement or you can enable the Vi keys (aka roguelike keys) in the config file. If numeric keypad doesn’t work, toggling the Num Lock key sometimes helps. If running with the Shift key and keypad keys doesn’t work, try Control key instead. The game is fully playable with mouse only, as well as with keyboard only, but the most efficient combination for some players is mouse for go-to, inspecting, and aiming at distant positions and keyboard for everything else.

If you are using a terminal frontend, numeric keypad may not work correctly depending on versions of the libraries, terminfo and terminal emulators. Toggling the Num Lock key may help. The curses frontend is not fully supported due to the limitations of the curses library. With the vty frontend started in an xterm, Control-keypad keys for running seem to work OK, but on rxvt they do not. The commands that require pressing Control and Shift together won’t work either, but fortunately they are not crucial to gameplay.

Compilation of the library and sample game from source

If you want to compile native binaries from the source code, use Cabal (already a part of your OS distribution, or available within The Haskell Platform7), which also takes care of all the dependencies.

The recommended frontend is based on SDL2, so you need the SDL2 libraries for your OS. On Linux, remember to install the -dev versions as well, e.g., libsdl2-dev and libsdl2-ttf-dev on Ubuntu Linux 16.04. (Compilation to JavaScript for the browser is more complicated and requires the ghcjs15 compiler and optionally the Google Closure Compiler16 as well.)

The latest official version of the LambdaHack library can be downloaded, compiled for SDL2 and installed automatically by Cabal from Hackage3 as follows

cabal update
cabal install LambdaHack

For a newer snapshot, clone the source code from github5 and run Cabal from the main directory

cabal install

There is a built-in black and white line terminal frontend, suitable for teletype terminals or a keyboard and a printer (but it’s going to use a lot of paper, unless you disable animations with --noAnim). To compile with one of the less rudimentary terminal frontends (in which case you are on your own regarding font choice and color setup and you won’t have the spiffy colorful squares around special positions, only crude highlights), use Cabal flags, e.g,

cabal install -fvty

Testing and debugging

The Makefile contains many sample test commands. Numerous tests that use the screensaver game modes (AI vs. AI) and the teletype frontend are gathered in make test. Of these, travis runs test-travis on each push to github. Test commands with prefix frontend start AI vs. AI games with the standard, user-friendly frontend.

Run LambdaHack --help to see a brief description of all debug options. Of these, the --sniff option is very useful (though verbose and initially cryptic), for displaying the traffic between clients and the server. Some options in the config file may prove useful too, though they mostly overlap with commandline options (and will be totally merged at some point).

You can use HPC with the game as follows (details vary according to HPC version).

cabal clean
cabal install --enable-coverage
make test
hpc report --hpcdir=dist/hpc/dyn/mix/LambdaHack --hpcdir=dist/hpc/dyn/mix/LambdaHack-xxx/ LambdaHack
hpc markup --hpcdir=dist/hpc/dyn/mix/LambdaHack --hpcdir=dist/hpc/dyn/mix/LambdaHack-xxx/ LambdaHack

A quick manual playing session after the automated tests would be in order, as well, since the tests don’t touch the topmost UI layer. Note that a debug option of the form --stopAfter* is required to cleanly terminate any automated test. This is needed to gather any HPC info, because HPC requires a clean exit to save data files.

Coding style

Stylish Haskell is used for slight auto-formatting at buffer save; see .stylish-haskell.yaml. As defined in the file, indentation is 2 spaces wide and screen is 80-columns wide. Spaces are used, not tabs. Spurious whitespace avoided. Spaces around arithmetic operators encouraged. Generally, relax and try to stick to the style apparent in a file you are editing. Put big formatting changes in separate commits.

Haddocks are provided for all module headers and for all functions and types from major modules, in particular the modules that are interfaces for a whole directory of modules. Apart of that, only very important functions and types are distinguished by having a haddock. If minor ones have comments, they should not be haddocks and they are permitted to describe implementation details and be out of date. Prefer assertions to comments, unless too verbose.

Further information

For more information, visit the wiki4 and see PLAYING.md, CREDITS and COPYLEFT.

Have fun!

Changes

v0.8.3.0

  • Add a hack to run SDL2 on the main thread, fixing the OS X crash
  • Warn visually when impressed and Calm running low, risking domination
  • Display actor as red when low Calm and impressed or when low HP
  • Fix, complete and fine tune UI, AI and server skill and weapon checks
  • Fix a bug where item aspects look different to clients than to the server
  • Change the requirements for the main menu ASCII art

v0.8.1.2

  • Fix typos detected by lintian
  • Fix the code that runs in case of old async (bug introduced in v0.8.1.1)

v0.8.1.1

  • no player-visible changes
  • make it possible to compile with old async package
  • rewrite copyright information according to Debian format
  • make github display the correct main license

v0.8.1.0

  • no player-visible changes
  • significantly reduce RAM usage when compiling library
  • update and extend CI

v0.8.0.0, aka ‘Explosive dashboard’

  • rework greying out menu items and permitting item application and projection
  • rework history collection; merge message repetitions more aggressively
  • display HP in red when below (configurable) warning threshold
  • tweak AI: actors remember they are fleeing; better leader choice, etc.
  • add to content specialized explosive projectiles; tune the effects
  • calculate loot score component based on fraction of dungeon loot collected
  • don’t hardwire item price, but let it be specified in content
  • let all valuables glitter in the dark to avoid complete level exploration
  • teach AI to cure ailments and shake off impressions
  • rework detection effects; add detection of items embedded in tiles
  • automatically identify stolen items that only have minor effects
  • let projectiles hit each other if fragile and substantial enough
  • rework item kind identification code; change the way it’s defined in content
  • make more item kinds (including some traps) secret
  • protect paralyzed actors with a stasis condition to avoid infinite paralysis
  • implement dumping screenshots in SDL2 and create animated GIFs in Makefile
  • generate most common consumables less often, but in depth-scaled bunches
  • make pushed actors alter tiles and trigger effects of embedded items
  • validate and cross-validate more content; reduce content creation boilerplate
  • make summoning more varied and prevent chain-summoning
  • add many ways to conditionally sequence effects
  • create large, merged rooms more often
  • generalize the terrain altering player command (C-c, mouse)
  • let RET, SPACE and ESC clear pending messages, if any
  • add dashboard with links to all menus and info screens
  • scale some organ and trap power with level depth
  • simplify level-scaled dice roll semantics
  • change scaled dice notation ‘dl’ to ‘dL’ for readability in-game
  • rebalance items and decrease dice variety to unclutter backpack
  • colour-code beneficial and harmful conditions in menu and in HUD
  • display item lore (also for organs, embedded items, explosions, etc.)
  • display embedded item descriptions as if they were tile descriptions
  • tweak blast visuals, lower particle counts, beautify their spread
  • tweak projectile visuals, e.g., display an extra frame when projectile dies
  • add intro screen and work on other ways to convey story
  • simplify a lot of code, including a bit of game rules
  • fix some bugs, tweak content, speed up some AI bottlenecks

v0.7.1.0, aka ‘Ancient troubles’

  • add amazing cave and item (actor, blast, organ) descriptions
  • package for Windows as an installer and also as zip archives
  • fix a crash from SDL frontend under some OpenGL drivers (no thread-safety)
  • add WWW address to the Main Menu, for other sites that may run our JS blob

v0.7.0.0, aka ‘The dice are cast’

  • decouple tile searching from tile alteration
  • refrain from identifying items that are not randomized
  • switch away from incapacitated leader to let others revive him
  • make rescue easier by not going into negative HP the first time
  • fix crowd of friends on another level slowing even actors that melee
  • fix missing report about items underneath an actor when changing levels
  • API breakage: change the syntax of dice in content
  • API addition: introduce cave descriptions
  • keep all client states in the server and optimize communication with clients
  • improve item choice for identification and item polymorphing
  • reset embedded items when altering tile
  • replace atomic command filtering with exception catching
  • reimplement dice as symbolic expressions inducing multiple RNG calls
  • switch to optparse-applicative and rewrite cli handling
  • add stack and cabal new-build project files
  • improve haddocks across the codebase

v0.6.2.0, aka ‘Zoom out’

  • make fireworks slower and so easier to spot
  • make rattlesnake deeper but more common
  • announce no effect of activation
  • describe original and current faction of an actor
  • highlight dominated actors
  • mark organs with comma instead of percent and gems with dollar
  • make the healing cave dangerous to prevent camping
  • slightly balance various content
  • by default move item the same as last time
  • often spawn between heroes and stairs going deeper
  • fix totalUsefulness computation for negative effects
  • fix abandoning distant enemy target despite no alternatives
  • fix slow pushing of actors
  • fix a crash when many actors run towards stairs
  • hotfix: Pass zoom keys through to the browser
  • help players find the info about changing the font size
  • depend on GHC >= 8.0 and new vector
  • specialize client code already in SampleMonadClient.hs
  • enable StrictData in all modules
  • replace ‘failure’ with ‘error’ that now shows call stack

v0.6.1.0, aka ‘Breaking one rule at a time’

  • fix redrawing after window minimized and restored
  • hack around vanishing texture on Windows
  • hack around SDL backends not thread-safe on Windows
  • the only breaking API change: specify font directory in game rules content
  • let the game use its own fonts, not fonts from the sample game in library
  • tweak some item creation to occur in character’s pack, not on the ground
  • slightly balance various content
  • make sure the ‘resolution’ effect is not a drawback
  • make artifact weapon rarities more regular
  • avoid creating lit, open dungeon at the bottom, where foes have ranged weapons
  • number scenarios in user descriptions
  • correct, add and modify some in-game messages
  • let player hear unseen summonings performed by other actors
  • don’t let actors hear blasts hitting walls, as opposed to hitting actors
  • when moving item out of shared stash, reset its timeouts
  • when ascending, shift timeouts of inventory as well
  • when creating item not on the ground, discover it
  • when dominating, auto-discover only if the item can’t be discovered by use
  • let henchmen take into account their targets, as described in PLAYING.md
  • let only walkable tiles be explorable, for clear walls inside solid blocks
  • move to API 2.0.0 of sdl2-ttf and depend on corrected sdl2 (builds on Windows)
  • simplify code thanks to the new sdl2-ttf API
  • tweak travis scripts and building docs in README

v0.6.0.0, aka ‘Too much to tell’

  • add and modify a lot of content: items, tiles, embedded items, scenarios
  • improve AI: targeting, stealth, moving in groups, item use, fleeing, etc.
  • make monsters more aggressive than animals
  • tie scenarios into a loose, optional storyline
  • add more level generators and more variety to room placement
  • make stairs not walkable and use them by bumping
  • align stair position on the levels they pass through
  • introduce noctovision
  • increase human vision to 12 so that normal speed missiles can be sidestepped
  • tweak and document weapon damage calculation
  • derive projectile damage mostly from their speed
  • make heavy projectiles better vs armor but easier to sidestep
  • improve hearing of unseen actions, actors and missiles impacts
  • let some missiles lit up on impact
  • make torches reusable flares and add blankets for dousing dynamic light
  • add detection effects and use them in items and tiles
  • make it possible to catch missiles, if not using weapons
  • make it possible to wait 0.1 of a turn, at the cost of no bracing
  • improve pathfinding, prefer less unknown, alterable and dark tiles on paths
  • slow down actors when acting at the same time, for speed with large factions
  • don’t halve Calm at serious damage any more
  • eliminate alternative FOV modes, for speed
  • stop actors blocking FOV, for speed
  • let actor move diagonally to and from doors, for speed
  • improve blast (explosion) shapes visually and gameplay-wise
  • add SDL2 frontend and deprecate GTK frontend
  • add specialized square bitmap fonts and hack a scalable font
  • use middle dot instead of period on the map (except in teletype frontend)
  • add a browser frontend based on DOM, using ghcjs
  • improve targeting UI, e.g., cycle among items on the map
  • show an animation when actor teleports
  • add character stats menu and stat description texts
  • add item lore and organ lore menus
  • add a command to sort item slots and perform the sort at startup
  • add a single item manipulation menu and let it mark an item for later
  • make history display a menu and improve display of individual messages
  • display highscore dates according to the local timezone
  • make the help screen a menu, execute actions directly from it
  • rework the Main Menu
  • rework special positions highlight in all frontends
  • mark leader’s target on the map (grey highlight)
  • visually mark currently chosen menu item and grey out impossible items
  • define mouse commands based on UI mode and screen area
  • let the game be fully playable only with mouse, use mouse wheel
  • pick menu items with mouse and with arrow keys
  • add more sanity checks for content
  • reorganize content in files to make rebasing on changed content easier
  • rework keybinding definition machinery
  • let clients, not the server, start frontends
  • version savefiles and move them aside if versions don’t match
  • lots of bug fixes internal improvements and minor visual and text tweaks

v0.5.0.0, aka ‘Halfway through space’

  • let AI put excess items in shared stash and use them out of shared stash
  • let UI multiple items pickup routine put items that don’t fit into equipment into shared stash, if possible, not into inventory pack
  • re-enable the ability to hear close, invisible foes
  • add a few more AI and autonomous henchmen tactics (CTRL-T)
  • keep difficulty setting over session restart
  • change some game start keybindings
  • replace the Duel game mode with the Raid game mode
  • various bugfixes, minor improvements and balancing

v0.4.101.0, aka ‘Officially fun’

  • the game is now officially fun to play
  • introduce unique boss monsters and unique artifact items
  • add animals that heal the player
  • let AI gang up, attempt stealth and react to player aggressiveness
  • spawn actors fast and close to the enemy
  • spawn actors less and less often on a given level, but with growing depth
  • prefer weapons with effects, if recharged
  • make the bracing melee bonus additive, not multiplicative
  • let explosions buffet actors around
  • make braced actors immune to translocation effects
  • use mouse for movement, actor selection, aiming
  • don’t run straight with selected actors, but go-to cross-hair with them
  • speed up default frame rate, slow down projectiles visually
  • rework item manipulation UI
  • you can pick up many items at once and it costs only one turn
  • allow actors to apply and project from the shared stash
  • reverse messages shown in player diary
  • display actor organs and stats
  • split highscore tables wrt game modes
  • move score calculation formula to content
  • don’t keep the default/example config file commented out; was misleading
  • I was naughty again and changed v0.5.0.0 of LambdaHack content API slightly one last time

v0.4.100.0, aka ‘The last thaw’

  • unexpectedly thaw and freeze again v0.5.0.0 of LambdaHack content API
  • unexpectedly implement timeouts and temporary effects easily without FRP
  • make a couple of skill levels meaningful and tweak skills of some actors
  • make AI prefer exploration of easier levels
  • permit overfull HP and Calm
  • let non-projectile actors block view
  • make colorful characters bold (if it resizes your fonts, turn off via colorIsBold = False in config file or –noColorIsBold on commandline)
  • start the game with a screensaver safari mode
  • add i386 Linux and Windows compilation targets to Makefile

v0.4.99.0, aka ‘Player escapes’

  • balance the example game content a bit (campaign still unbalanced)
  • various code and documentation tweaks and fixes
  • add cabal flag expose_internal that reveals internal library operations
  • merge FactionKind into ModeKind and rework completely the semantics
  • compatibility tweaks for Nixpkgs
  • define AI tactics, expose them to UI and add one more: follow-the-leader
  • share leader target between the UI and AI client of each faction
  • specify monster spawn rate per-cave
  • extend content validation and make it more user friendly
  • freeze v0.5.0.0 of LambdaHack content API

v0.2.14, aka ‘Out of balance’

  • tons of new (unbalanced) content, content fields, effects and descriptions
  • add a simple cabal test in addition to make-test and travis-test
  • generate items and actors according to their rarities at various depths
  • redo weapon choice, combat bonuses and introduce armor
  • introduce skill levels for abilities (boolean for now, WIP)
  • remove regeneration, re-add through periodically activating items
  • ensure passable areas of randomly filled caves are well connected
  • make secondary factions leaderless
  • auto-tweak digital line epsilon to let projectiles evade obstacles
  • add shrapnel (explosions) and organs (body parts)
  • express actor kinds as item kinds (their trunk)
  • add dynamic lights through items, actors, projectiles
  • fix and improve item kind and item stats identification
  • make aspects additive from all equipment and organ items
  • split item effects into aspects, effects and item features
  • rework AI and structure it according to the Ability type
  • define Num instance for Dice to make writing it in content easier
  • remove the shared screen multiplayer mode and all support code, for now
  • rename all modules and nearly all other code entities
  • check and consume HP when calling friends and Calm when summoning
  • determine sight radius from items and cap it at current Calm/5
  • introduce Calm; use to hear nearby enemies and limit item abuse before death
  • let AI actors manage items and share them with party members
  • completely revamp item manipulation UI
  • add a command to cede control to AI
  • separate actor inventory, 10-item actor equipment and shared party stash
  • vi movement keys (hjklyubn) are now disabled by default
  • new movement keyset: laptop movement keys (uk8o79jl)

v0.2.12

  • improve and simplify dungeon generation
  • simplify running and permit multi-actor runs
  • let items explode and generate shrapnel projectiles
  • add game difficulty setting (initial HP scaling right now)
  • allow recording, playing back and looping commands
  • implement pathfinding via per-actor BFS over the whole level
  • extend setting targets for actors in UI tremendously
  • implement autoexplore, go-to-target, etc., as macros
  • let AI use pathfinding, switch leaders, pick levels to swarm to
  • force level/leader changes on spawners (even when played by humans)
  • extend and redesign UI bottom status lines
  • get rid of CPS style monads, aborts and WriterT
  • benchmark and optimize the code, in particular using Data.Vector
  • split off and use the external library assert-failure
  • simplify config files and limit the number of external dependencies

v0.2.10

  • screensaver game modes (AI vs AI)
  • improved AI (can now climbs stairs, etc.)
  • multiple, multi-floor staircases
  • multiple savefiles
  • configurable framerate and combat animations

v0.2.8

  • cooperative and competitive multiplayer (shared-screen only in this version)
  • overhauled searching
  • rewritten engine code to have a single server that sends restricted game state updates to many fat clients, while a thin frontend layer multiplexes visuals from a subset of the clients

v0.2.6.5

  • this is a minor release, primarily intended to fix the broken haddock documentation on Hackage
  • changes since 0.2.6 are mostly unrelated to gameplay:
    • strictly typed config files split into UI and rules
    • a switch from Text to String throughout the codebase
    • use of the external library miniutter for English sentence generation

v0.2.6

  • the Main Menu
  • improved and configurable mode of squad combat

v0.2.1

  • missiles flying for three turns (by an old kosmikus’ idea)
  • visual feedback for targeting
  • animations of combat and individual monster moves

v0.2.0

  • the LambdaHack engine becomes a Haskell library
  • the LambdaHack game depends on the engine library
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