They're certainly better than I could do - but then, I'm not doing a design course, either. I think, perhaps, if each character had a less "polished" and shiny appearance they'd fit into a game quite well, although it depends on what game genre, etc., also. They're nice looking, but if you tweaked them a little bit as suggested they may look better (or worse, of course...).

Anyway, I'll chuck this across to fanart; there you'll likely get better responses and more substantial comments to do with what can be improved, etc.