OpenTyrian is a port of Tyrian, a classic DOS game. The port was made to C using SDL, so it can run cross-platform without DOSBox.
We have been given a copy of the original Turbo Pascal source to look at but not redistribute. The initial C port will be a direct port with minimal changes and will serve as a freely-distributable reference implementation thereafter.
If you'd prefer to build OpenTyrian yourself, checkout a copy of the source and...
Checking out source
Please disregard the instructions on the source page. To download a working copy of the main project source, use:
svn checkout http://opentyrian.googlecode.com/svn/classic/trunk/ opentyrian