This surely is a candidate for Monday Morning Time Waster. You are a boy that fell into a cave and the goal is to climb out again (only that the cave is infinitely deep). On your way up you kill slimes, collect diamonds and try to survive by climbing higher and higher while the screen moves upwards faster the higher you get. After you die you can buy upgrades like higher movement speed, a double jump or more health with the diamonds you have collected. Highly addicting!