Round Death

Round Death is an easter egg in the Duck Hunt room in Act I.

How to
After you survive 3 brutal rounds in the Duck Hunt level, you can either "fly away" and proceed to the next screen by jumping out of view to the right, or, stay on the screen and endure Round Death. This is near impossible and has yet to be completed. If you were to complete this round you would be teleported to a secret room with treasures unknown. Most people that have completed 3 rounds have moved on to the next screen not knowing that there is anything past the three rounds, thus keeping this one of the best secrets in the game.

So far there is one person ever to have lived through it.