A game where you start on a rowboat lost at sea. On the rowboat, you must survive sharks...but really, it is the sun, hunger, thirst and giant ass waves....and storms...
Now from here, you can either find an island (if lucky), which leads to finding a tribe (very rare) that can be savage (likely) or friendly (rare) or just a barren dead island (likely). It can also randomize island...that island might be the deadliest island on the map...1 snake for every square foot, as many or more spiders...all the deadliest animals in the world. Game over. Or you can find a nice peaceful island like in the typical movies. Not likely. (edit: Some other islands could be a lost prehistoric island, a caveman island, a zombie island, a cyborg island...whatever...random ass islands...hey even a clown island! Now that be scary as hell. Cause why the hell not!)
Most islands will have problems if they are too low sea level. One hurricane or even storm will flood the entire island. But maybe you built a better boat to get away? Get up and leave again! Unless you found a large island...mostly save...then it turns to survival against any hurricanes. Of course, hurricanes would be really rare cause otherwise too annoying.
Land on a continent? You win! CONGRATULATIONS WINDOW POPS UP FOR 1000 points....JK! Its a radioactive wasteland fool! THATS WHY YOU LEFT ON A ROWBOAT! GAME OVER! SUICIDE!
Want to play multiplayer? Great! You took yourself and X number of friends on a rowboat! Want to play with 20 or 50 or 1000000000 friends? ITS A BIG ROWBOAT. But you can't populate, you are radiated and infertile. One friend dies, its permanent. Cause no freakin cheap ass respawns for U!
Find a secret island military base (SUPER RARE WOOOOO)...now find that radioactive suit filled with an island of angry aliens that escaped the base. You will see they wear diplomatic clothing, but hey they got shot down by gun happy military! Succeed? The game opens whole new continent...where you find a friendly diplomatic alien mission where aliens wanted to give hi-tech stuff to help humans, ended up in world war 3...extra terrestrials vs humans...and the aliens are SUPER advanced and almost impossible to kill. How to survive? Hide...and be stealthy...get in close and quiet if needed...find a place to make a base? Great, maybe one day you can make a nice stronghold for yourself. Or hide in the woods and hunt and survive!
Or/and play high stake missions of saving humans in test tubes that the aliens put in...cause they wanted to take revenge upon thee humans!!!!
It be best game over. There would be NPCs to populate islands or test tubes, but even in multiplayer, REALLY hard to get...and you could get friendly tribes to join you, but that be rare and take a long time. But all worth it in the end, cause they'd help a lot. And the ones in test tubes could be mutated humans or something since it give a reason to save them...VERY strong and evolved humans who, while still have a hard time against aliens (or near impossible for a bad strategist), would help tremendously if using enough strategy and tactics.