I've always liked survival as a backdrop to a full fledged RPG, instead of the entire focus. Like a barbarian type character hunting and gathering in a cold, desolate stretch of plains. Skinning animals and building up a shelter and so on but still having the option to fight something besides deer and elk

I think something with cavemen would be kinda neato too, before any modern inventions and somehow with rules to really capture a brutal existence.
Or going futuristic and doing a survival game on a different planet, since then you could really flesh out learning about new plants and animals as part of it. Like maybe their spaceship crashed and they need to survive until a rescue comes. I think having a definite goal and end would help.