Well, there is a new 3D engine in development here. Please post your support in the Dreamcast port thread.http://www.cubicvr.org/index.php?option ... e&Itemid=1
Also some people are developing Half-Life mods for Dreamcast, but the engine is pretty limited on what you can actually do. I would say so far it has the best graphics for homebrew projects.
[link removed (warez) -BlueCrab]
About ScummVM, yes there is a port of that, but it is not really a game engine, more along the lines of an interpreter for old point and click games.http://www.scummvm.org/