I approve of game writing competitions, especially if specifically restricted to certain hardware, or with categories of prizes/competition (e.g., Best 64kb game, Best OCS game, Best AGA game, Best Audio, Best Graphics, Best New Idea). I also agree that people need reasonable time limits to implement things.
It's easy for the MSX dudes to do games for competitions - the computer's resources are limited. You could do a game on the MSX in a month of evenings (and the same for other eight bitters) if you already knew the system. On the Amiga the graphics takes four times as long and the game can be ten times more complex.
So I suggest - Porting Old 8-Bit Games Competition. You find a game on any 8-bit platform and create an Amiga version. This also opens the competition up for Amos and Blitz Basic users as even a stock A500 has enough performance here. We can therefore also add "Most Faithful Conversion" as a prize!