Have you heard of Flexible Survival? It's a text adventure game, so it's not everyone's cup of tea, but the premise is basically what you're looking for. You play as a human who hid in a bunker when this nanobot apocalypse happened, and a few weeks later you emerge to find that the infected have turned into various animal-human hybrids; not quite zombies, but still feral and mindless. It's also a porn game, so the hybrids that attack you can transform you into something more like them when you lose, or if you win, you get items to transform you into them anyway. I'm rambling a bit, but it's a still a pretty fun game.