I've begun a port of the Atari ST game Sundog: Frozen Legacy to modern platforms with SDL and OpenGL ES 2. This is not a complete remake: it emulates the p-system interpreter that the original game ran in, on current hardware. A few 68000 assembly routines that it called out to did have to be reverse-engineered and re-implemented.
It is basically playable though not completely tested, there may still be a few flukes left.
Code can be found here: https://github.com/laanwj/sundog