Oddest Systems You've Ever Played (Mechanically/Setting Wise)

i guess this is a topic about some of the weirdest games we've ever played, whether it be because the game's system is so odd or because the game's setting is so off-beat.  Weirdest game I ever played was actually Continuum: Roleplaying in the Yet. I was actually GMing this game and found myself wrestling a lot with how the game dealt with time travel and combat specifically. In terms of both mechanics and setting, the game was really lavish but the rolls themselves got really difficult, especially with the addition of time traveling working into combat. The game only lasted a session since it took me about two hours to make heads or tails of everything. I looked up the core rulebook on Amazon and it turns out that people are selling it for over a hundred bucks. Lol. 

Kobolds Ate my Baby - I have played it as a drinking RPG with lots of house rules. In college had a room mate who ran a "Death of A Salesman" RPG; laughable and depressing, remember I did not make my sales quota and another player as my wife would berate me.

I had a friend run a game once that had no rules at all. We played ourselves with whatever was actually in our pockets. The setting was that we were all in a room that was all white with no doors or windows. None of us figured out how to get out. The game lasted one night until we got bored. Then we took acid. Yes this was in the 80's. True story.

I remember the first times I played Mage the Ascension, everyone in my table was in love with the way magic worked; it was amazing, broad and made you feel like you could do anything. Of course it was also hard, not mechanically, it was just hard to wrap your head around it and get accustomed to it. In the beginning no one was using it, hahaha. The first sessions we saw very little magic, and when it happened it was very basic: an explosion here, an invisibility spell there, flying, stuff like that. When we got better at understanding the game and we read some supplements that's when things started to get crazy: Manipulation of time and space, creation of life and elements with weird properties, fireballs that would not hurt you but would steal your memories, spells that let you find a specific person or thing wherever it is in the world, cloning oneself, sharing of senses. I loved that system of magic, so far no other comes even close for me.