Atari Pitfall, now that was a hard jungle survival game...

As Pitfall Harry, you are tasked with collecting all the treasures in a jungle within 20 minutes.

The world consists of 255 screens which are horizontally connected in a flip screen manner. Each screen has one or more hazards: quicksand, tar pits (<--Valheim copied that), rolling logs, (again copied by Valheim) crocodiles, snakes, scorpions, campfires, (copied again by Valheim) and swinging vines. All versions of the game sold over 5 million copies worldwide.

So if it wasn't for Pitfall, Valheim probably wouldn't even exist...