You can easily create plugins for the game by putting a new folder into plugins/ with the name of your plugin and then compiling your code into a shared library placed inside this folder named "<plugin name>.so" (`-shared -fpic`).
You might want to include the game.h file from plugins/game/game.h. Have a look into it to see available API. See the existing plugins for examples.
-Controls: WASD to move, Q to quit.
+Controls: WASD to move, Q to quit, Space to shoot.
To build the loader and the plugins in the plugins/ folder, simply type `make` or `make all`. There are separate targets for the loader (`dungeon`) and the plugins. All Makefiles that are placed in plugin directories, so you might want to include a makefile in your plugin. The plugins target simply depends on ${PLUGINS}, so just add things to this in your plugin Makefile to add them to the plugins target (usually your plugin.so)
To run the loader, type `./dungeon`. It will load all plugins including the game itself dynamically and run the game.