Nice concept. Love the idea of having an arena to survive in vs different enemies.
Impressive you've done all the art and such yourself. Great use of the rag doll features in unity.
What you've done in a week is great, this feedback relates more to farthing the project.
It'd be nice if I could use metro or UFO to kill off those Zombies :D.
Little bit more balance required. Few places to survive lava, and if the UFO is coming for you as well, feels like no chance :P.
think there's some great potential here. Well done!