If I had a decent monitor @ work I'd do it 4 ya, this sucks tho.
I'll give you an idea tho...
Use an high res image of either an object, character or map that identifys each game, 1 picture per layer. Spread the focal points out & blend the edges so that they run into each other. Then add a grungy bumpmap or transparency & write your name/slogan/logo over the top.
Could be done in Gimp easily enough...