The other ending, admittedly, is counter-intuitive in the way you unlock it.
== SPOILER WARNING==
I'll reveal it now so
You need to die multiple time to the enemies until the text at the top becomes a red "ID", and then you need to beat the game.
The reason it is the way it is, is because it makes the most sense thematically.
Thanks for playing my game! I'm glad you enjoyed it enough to try and get the other endings! :D