I never got to play with the tesseract idea, but I did steal the "Lost Woods" from the original Legend of Zelda video game for a dungeon.

I kept it simple--a four-way intersection that repeated unless they walked it in a specific pattern (I even kept it as the original solution). They figured it out in about 20 minutes thanks to a couple hints I put in other rooms. Always leave a few hints for the PCs. :3