If you liked old games like old Rick Dangerous, then here's another game named SPELUNKY.
The team development come with this intro:
"Legends speak of a Colossal Cave that extends deep underground, so twisted by time that its passages shift like the sand under which it lies... the Cave is said to be filled with fabulous treasures, but also incredible danger!"
The character of the game has a rope and whip that you can use to explore different areas of the game.
The keys
Read about this game here.