LambdaHack

LambdaHack is a [Haskell] 1 game engine library for [roguelike] 2 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 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.

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).

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

Compilation and installation

The library is best compiled and installed via Cabal (already a part of your OS distribution, or available within [The Haskell Platform] 7), which also takes care of all the dependencies. 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

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

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 gtk2hs-buildtools
cabal install -fvty

Some pre-compiled game binaries may be available from the [releases] 11 page.

Compatibility notes

The current code was tested with GHC 7.6 and 7.8, but should also work with other GHC versions.

If you are using the terminal frontends, numerical 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 run in an xterm, CTRL-keypad keys for running seem to work OK, but on rxvt they do not. Laptop (uk8o79jl) and Vi keys (hjklyubn, if enabled in config.ui.ini) should work everywhere regardless. GTK works fine, too.

Testing and debugging

The Makefile contains many sample test commands. All commands 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 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 that is used to gather HPC info, because HPC needs a clean exit (to save data files).

Further information

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

Have fun!