The last game I can find from the lemon amiga database is from 2005 called desert racing of bardos.
There have probably been others.
I too would refer to the Amiga as 16 bit, especially the earlier ones.
In the UK we always called the C64, amstrad etc 8 bit and the amiga/st 16 bit.
I doubt the early amiga/st computers were truly 32 bit.
On the lemon amiga forums there is a thread from a guy who has released a game called downfall recently.