In the game menu, go to Options>Graphics>Tint and select Atomic Fallout. The screen will tint green (this is a reference to the Fallout series). Then, go to Community>Editor>New Level and place a few objects. Close the game, and check your achievements and you will see a creepy face staring at you with a green tint as the achievement icon. If you're wondering what this is, t is a reference to the internet series "Don't Hug Me I'm Scared". You should watch it, just a fair warning it is a bit graphic.