I really wonder just how many "real" Amiga people there are left sometimes. Arguing over stupid crap seems more interesting to people than actually using thier amigas from what I can tell.
p.s. by "real" I mean people who dont just like to reminisce, or use thier Amiga's for more than a casual game on Winuae or similar from time to time.
I do use my old computers for more than just gaming, and I do have plans to put together an Amiga game or two in the not-too-distant future. Gotta get through MSXdev first, though.
As far as suggestions, if you're serious about getting this done in a month, pick something simple, like an Atari 2600 game, and give it a nice port/slight expansion, or a later game whose internals are well-documented enough that you can construct your own re-coding and supply the original maps/scripts with Amiga-tailored graphics and sound.