LambdaHack: A game engine library for roguelike dungeon crawlers

[ bsd3, game, game-engine, library, program, roguelike ] [ Propose Tags ]

LambdaHack is a game engine library for roguelike games of arbitrary theme, size and complexity, packaged together with a small example dungeon crawler.

When completed, the engine will let you specify content to be procedurally generated, define the AI behaviour on top of the generic content-independent rules and compile a ready-to-play game binary, using either the supplied or a custom-made main loop. Several frontends are available (GTK is the default) 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 vision revolves around procedural content generation and includes in-game content creation, auto-balancing and persistent content modification based on player behaviour.

Games known to use the LambdaHack library:

Note: All modules in this library are kept visible, to let games override and reuse them. OTOH, to reflect that some modules are implementation details relative to others, the source code adheres to the following convention. If a module has the same name as a directory, the module is the exclusive interface to the directory. No references to the modules in the directory are allowed except from the interface module. This policy is only binding when developing the library --- library users are free to access any modules, since the library authors are in no position to guess their particular needs.

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Versions [RSS] 0.1.20080412, 0.1.20080413, 0.1.20090606, 0.1.20110117, 0.1.20110918, 0.2.0, 0.2.1, 0.2.6,, 0.2.8, 0.2.10,,, 0.2.12, 0.2.14,,,,,,,,,,,,,,,,,,,,,,,,, (info)
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Dependencies array (>= && <1), assert-failure (>=0.1 && <1), async (>=2 && <3), base (>=4 && <5), binary (>=0.7 && <1), bytestring (>=0.9.2 && <1), containers (>= && <1), data-default, deepseq (>=1.3 && <2), directory (>= && <2), enummapset-th (>= && <1), filepath (>= && <2), ghc-prim (>=0.2), gtk (>=0.12.1 && <0.14), hashable (>= && <2), hsini (>=0.2 && <2), keys (>=3 && <4), LambdaHack, miniutter (>=0.4.4 && <2), mtl (>=2.0.1 && <3), old-time (>= && <2), pretty-show (>=1.6 && <2), random (>=1.1 && <2), stm (>=2.4 && <3), template-haskell (>=2.6 && <3), text (>= && <2), transformers (>=0.3 && <1), unordered-containers (>=0.2.3 && <1), vector (>=0.10 && <1), vector-binary-instances (>=0.2 && <1), zlib (>= && <1) [details]
License BSD-3-Clause
Author Andres Loeh, Mikolaj Konarski
Maintainer Mikolaj Konarski <>
Category Game Engine, Game
Home page
Bug tracker
Source repo head: git clone git://
Uploaded by MikolajKonarski at 2015-04-18T00:01:37Z
Distributions Arch:, Debian:, LTSHaskell:, NixOS:
Reverse Dependencies 2 direct, 0 indirect [details]
Executables LambdaHack
Downloads 30006 total (92 in the last 30 days)
Rating 2.25 (votes: 2) [estimated by Bayesian average]
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Readme for LambdaHack-

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LambdaHack Build StatusBuild Status

LambdaHack is a [Haskell] 1 game engine library for [roguelike] 2 games of arbitrary theme, size and complexity. You specify the content to be procedurally generated, including game rules and AI behaviour. 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 (GTK is the default) 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 and content and of clients (human and AI-controlled) and server. Long-term goals for LambdaHack include support for multiplayer tactical squad combat, in-game content creation, auto-balancing and persistent content modification based on player behaviour.

The engine comes with a sample code for a little dungeon crawler, called LambdaHack and described in

gameplay screenshot

Other games known to use the LambdaHack library:

  • [Allure of the Stars] 6, a near-future Sci-Fi game
  • [Space Privateers] 8, an adventure game set in far future

Note: the engine and the example game are bundled together in a single [Hackage] 3 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 Stars] 10 or any other pure game content package 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 tradition] 9, 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).

Installation from binary archives

Pre-compiled game binaries for some platforms are available through the [release page] 11 and from the [Nix Packages Collection] 12. To manually install a binary archive, make sure you have the GTK libraries suite on your system, unpack the LambdaHack archive and run the executable in the unpacked directory.

On Windows, if you don't already have GTK installed (e.g., for the GIMP picture editor) please download and run (with default settings) the GTK installer from

Screen and keyboard configuration

The game UI can be configured via a config file. A file with the default settings, the same as built into the binary, is in GameDefinition/config.ui.default. When the game is run for the first time, the file is copied to the official location, which is ~/.LambdaHack/config.ui.ini on Linux and C:\Users\<username>\AppData\Roaming\LambdaHack\config.ui.ini (or C:\Documents And Settings\user\Application Data\LambdaHack\config.ui.ini or something else altogether) on Windows.

Screen font can be changed and enlarged by editing the config file at its official location or by CTRL-right-clicking on the game window.

If you use the numeric keypad, use the NumLock key on your keyboard to toggle the game keyboard mode. With NumLock off, you walk with the numeric keys and run with SHIFT (or CONTROL) and the keys. This mode is probably the best if you use mouse for running. When you turn NumLock on, the reversed key setup enforces good playing habits by setting as the default the run command (which automatically stops at threats, keeping you safe) and requiring SHIFT (or CONTROL) for the error-prone step by step walking.

If you don't have the numeric keypad, you can use laptop keys (uk8o79jl) or you can enable the Vi keys (aka roguelike keys) in the config file.

Compilation from source

If you want to compile your own binaries from the source code, use Cabal (already a part of your OS distribution, or available within [The Haskell Platform] 7), which also takes care of all the dependencies. You also need the GTK libraries for your OS. On Linux, remember to install the -dev versions as well. On Windows follow [the same steps as for Wine] 13. On OSX, if you encounter problems, you may want to [compile the GTK libraries from sources] 14.

The latest official version of the library can be downloaded, compiled and installed automatically by Cabal from [Hackage] 3 as follows

cabal install gtk2hs-buildtools
cabal install LambdaHack --force-reinstalls

For a newer snapshot, download source from a development branch at [github] 5 and run Cabal from the main directory

cabal install gtk2hs-buildtools
cabal install --force-reinstalls

For the example game, the best frontend (wrt keyboard support and colours) is the default gtk. To compile with one of the terminal frontends, use Cabal flags, e.g,

cabal install -fvty --force-reinstalls

Compatibility notes

If you are using a terminal frontend, numeric keypad may not work correctly depending on versions of the libraries, terminfo and terminal emulators. The curses frontend is not fully supported due to the limitations of the curses library. With the vty frontend started in an xterm, CTRL-keypad keys for running seem to work OK, but on rxvt they do not. The commands that require pressing CTRL and SHIFT together won't work either, but fortunately they are not crucial to gameplay. For movement, laptop (uk8o79jl) and Vi keys (hjklyubn, if enabled in config.ui.ini) should work everywhere. GTK works fine, too, both with numeric keypad and with mouse.

Testing and debugging

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

Run LambdaHack --help to see a brief description of all debug options. Of these, --sniffIn and --sniffOut are very useful (though verbose and initially cryptic), for monitoring 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 (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).

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

Note that debug option --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.

Further information

For more information, visit the [wiki] 4 and see, CREDITS and LICENSE.

Have fun!