Pretty much every animal/human hybrid has been thought of already, used endlessly, and perverted by furry porn.
Let's see, stuff I've encountered in fiction...
Skroderiders, a breed of intelligent trees that have no short-term memory; they have to consult a memory bank in order to carry on a conversation. (A Fire on the Deep by Verner Vinge)
Tines, a dog-like race in which each pack is an individual, and individual pack members are thought of as body parts. (A Fire on the Deep by Verner Vinge)
All the hominid races of the Ringworld books by Larry Niven (which would make an awesome video game, I think), as well as some of his other races, the Kzinti, for example, tho they're sort of like nine foot tall cats with rat tails.
The thing about different races in a game, is that for the most part, people want to play something that's at least mostly human. Like elves, dwarves, werewolves, and furries, zombies, demons. What I'm more interrested in is how they balance the playable races and if they make sense.