DreamChess is a chess game by Phantom and Mr. Siggler. It runs on Dreamcast, Windows, Linux, and BeOS. The source is available in the link above. A ready to burn CDI image for the Dreamcast version is available here:
Also, Mr. Siggler mentioned that they are in need of 3D models, artwork, and eventually audio/music. The game already has the theme support -- take a look in the data folder on the disc, or drop a message in this thread on the DCEmulation boards if you want more info, and/or are interested in helping out.