Overview
First and foremost, we have a level editor. You can get at this by pressing ctrl-e anywhere in the game, and it’ll start editing the current level. The level editor will edit our levels in place, overwriting the core content in the game; thus, you’ll find any new levels you make inside the game data files, under ~/data/levels/. On windows/linux, the data folder is in the same folder as the .exe, whereas on mac, the data folder is inside the program icon; you can get at it by right-clicking on the icon, selecting Show Package Contents, and looking inside Content/Resources. (Naturally, everything else for the game, such as images and music, are in nearly the same place.)
On phone OSs like iOS, Android (coming soon?), and WebOS, the editor isn’t available yet. It’s probable due to the tiny screen size that we won’t end up doing it for anything less than iPad-sized tablets, since it would be nearly impossible to use on a tiny screen.
We’ve have a fairly extensive, but not quite comprehensive (yet) wiki full of documentation on how objects/tiles/etc are scripted.
What are your dependencies?
You’ll need OpenGL, GLEW, SDL (plus SDL_ttf, SDL_mixer, and SDL_image), and Boost (specifically regex and system). LibPNG is needed for making a ‘precompiled’ set of images to use on computers (it saves video-ram and makes the game run faster).
Source Code and License
Naturally, you’ll be interested to see our source code.
Our code is open-source, our content isn’t. We love the open-source movement, but because we’re trying to make money off of the project, we need legal protection against someone else selling it (or freely giving it away) when doing so would really hurt us. (Besides just dishonest people who want something for nothing, with an entirely permissive license, it’s legal for others to rebrand the game as if they made it, duping people into paying them instead of the original creators.) If we open-sourced everything, we’d have no protection at all. Overall, though, we’re huge fans of open-source, so if you want to reuse something we made that you’re not sure is open, please ask! We’ll probably say yes.
In fact, we’ve already done that with a few old tilesets and such: these can be found at OpenGameArt.
The license on the code is the GPL, but we’re doing a Qt-style dual-licensing model, so we insist that if you contribute something, you transfer the copyright to us. We of course immediately re-release it in our source tree as GPL, as you would want.
Further Resources
Our bug tracker. It is not a complete list of bugs fixed, as we use it mostly for longer-term issues. The wiki contains lots of reference material.
There are some old resources on Google Code. These have been abandoned for licensing reasons, and are no longer used.

