It was a literal nightmare, in that I dreapt it in my sleep, right before waking up in my bed. I shit you not.

So here's what it was. I was a Luigi sprite, complete with actor and state machine, inside a Super Mario Bros. cartridge hacked so that two players could play at the same time.

BIIIG mistake, because I don't think the game engine could take it. My state machine was going haywire. Soon I was swimming whether I was underwater, or in the air. And the stage Mario and I were on had both, for some reason.

I was starting to lose it. I was pleading with Mario to do something, but he didn't know what to do either. Next thing I knew, not only was I swimming in air, but now I was swimming in solid walls too. I had lost all collision detection entirely.

I'm not entirely sure on this last part, but I think I swam right through the flagpole and through the castle wall, without the game realising I had. I didn't know WHERE it was going to end, but then, I woke up.