BACKSTAB

You are in a jungle, or in a flooded city, or in a snowy tundra filled with dark woods and wild animals. Your mechs are red and gold war machines, sharp around the edges, or obsolete pieces of junk. The war has been going on for decades, or you may be the first generation of insurgents. It doesn't really matter, you are a team, and you only live for each other. 

And one of you is a traitor.