Deathworld: You and your crew has crashlanded on a world filled with deadly and violent creatures. Recover your technology and make use of your environment to survive the onsaulght intill you can repair your ship, or you are rescused. (Think tribal stage with mix of high and low techs, and lots of nasty animals)
Super-Predator: You are a genetical modifed Super cranivore, bred for war. However your transport has crashlanded on a primative world, killing all the crew and your brood mates, but one. Unfortunately, her transport section broke off in low orbit and could be any where. Your goal is to grow into maturity, eating the local fauna and tribal inhabitants, and sniff out your mate. (basically start as an infant, grow, and mate.)