There seems to be a new racing game for OS4 and MorphOS, and support may come for PPC Linux and even classic 68k Amiga later.

Here's a video:
https://www.youtube.com/watch?v=obMC53p4Qnc

And download link for MorphOS version:
http://amigatec.com/drupal/?q=node/123

Looks nice (Lotus/Outrun style), but gameplay is a bit too simple currently... not even at Lotus level what I quickly tried...