The basic game is running on a total of 8 groups:
The versatile Aliens, strong dinosaurs, the crooks that can be annoying really, the ninjas who hold some surprises, the flexible pirates, robots that are strong especially in large numbers, the wizards who for much "extra" (Extra-cards, extra creatures and extra actions) care and not to forget: the zombies that are just go on forever.
The illustrations are beautifully designed (especially the pirates have it done to me), the fractions are fun and provide with their unique mechanics even after many rounds yet for lots of fun - alone with the basic game are 56 fraction combinations are possible (whereby favorites and less popular will emerge fractions relatively quickly).