It is somewhat in the game. If you play Blockland in the month of October theres a rare chance that a face will appear off in the distance every so often.
This.
In case you weren't already aware, I made the renderman mod. It's based off a secret script Badspot embedded in an add-on called Brick_Haloween or something which would cause faces to appear in random places on dark maps. 2Spooky4U, amarite?
There's probably somewhere you can download the old code, since the community quickly found it.