LambdaHack is a Haskell game engine library for roguelike 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 PLAYING.md.
Other games known to use the LambdaHack library:
- Allure of the Stars, a near-future Sci-Fi game
- Space Privateers, an adventure game set in far future
Note: the engine and the example game are bundled together in a single
Hackage package released under the permissive
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
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,
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 and from the Nix Packages Collection. 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
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:\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), 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. On OSX, if you encounter problems, you may want to compile the GTK libraries from sources.
The latest official version of the library can be downloaded, compiled and installed automatically by Cabal from Hackage as follows
cabal update cabal install gtk2hs-buildtools cabal install LambdaHack --force-reinstalls
For a newer snapshot, download source from a development branch at github 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
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
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.
LambdaHack --help to see a brief description of all debug options.
--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 (details vary according to HPC version). 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-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
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.