Lewis, r n r nYou could have them design a game to be played on a physical medium like pen paper, a board game, etc. and then play a run-through of it. If it sucks, then they are probably not a good game designer.
Awesome article I 'm about 4 years into a web-driven, grid-based game, and I think you just gave me the cajones to finally release what I have and then iterate for new features based on player reaction. Cheers