Easy "Oops" Achievement...
	Various Steam Achievements...

When the Stranger gives you the choice between the left and right portal at the ending, choose the left one.

Achievement	Description
Annoying spikes	Die 100 times from spikes.
Die. Respawn. Repeat.	Die 1000 times.
Finally!	Complete the game.
First death	Die for the first time.
Flying death	Die 100 times from flying spikes.