Don't forget NES, SNES and Genesis. 2d games are way easier for small kids like 3-4yo. I personally would recommend Mickey Mouse and Donald Duck in World of Illusions as you do Coop and can save the kid a lot.

I was surprised that children that didn't grow up with the graphic revolution, does not seem to care about graphics. They don't seem to care they are playing 40-30 year old games.