What game? hmmm that's a tough one.
It's like asking what car people would like to buy..> everyone's got different tastes.
I rekon if you do something You like, and it's good enough, gamers will go for it.
The amiga is great for retro gaming so maybe an updated retro game would be a good choice. Personally i'd like a film-tie in game, something like robocop 3 with different levels or even an updated version of 'The killing Cloud' (no tie-in with current events intended!) or even a 3d shooter like 'Virus' from the Archimedes and Amiga vesion.
Failing that, how about a transforming robot toaster that fights other transforming houshold objects eh?
That's enough of my way-out suggestions, good luck with it!