Speaking as the owner and director of a games company, I can tell you now there is no way I would consider writing just for AmigaOS unless someone was paying me up front, because the numbers are just far too small. If you can get me £100,000 I'll get the guys started on a small game if you like, that should cover about 12 months work (as we're a very small company so we're very cheap compared to most) so we should be able to get a nice little game up.
Of course for your £100,000 you'll probably see sales - if we do a REALLY successful game - of about £10,000.
You might have a hard time getting financing with those numbers.
Honestly, I'm as pro-Amiga as anyone but seriously, the days of the Amiga as a commercial gaming platform are long gone. Heck, I wouldn't even want to do a game on the PC, which is a billion times the bigger platform, because there's no point - you can get much more return on a 360 or PS3.
For gaming, consoles have taken over the market.