When have glitches improved a game?

[Legend]

In Deathloop the quest system broke halfway through. I thought it was normal, so I had a great time figuring out what I should do instead of just following a checklist.

[kitler53]

I wouldn't exactly say it "improved" the game but once while playing killzone 3 mp a guy showed me how to platform out of the map into the wireframing above the map.  

we could have cheated from there and I'm sure people have but we spent our time platforming to the outer most edge of the map. 

it was a lot of fun.  so much so it almost makes me think developers should on occasion make this sort of area on purpose.  as long as the area is completely optional it was a neat experience. 

[Legend]

I wouldn't exactly say it "improved" the game but once while playing killzone 3 mp a guy showed me how to platform out of the map into the wireframing above the map.  

we could have cheated from there and I'm sure people have but we spent our time platforming to the outer most edge of the map.

it was a lot of fun.  so much so it almost makes me think developers should on occasion make this sort of area on purpose.  as long as the area is completely optional it was a neat experience.

There was a similar out of bounds glitch in Halo I loved back in the day.

There is also the famous Gandhi glitch from civilization. Made him love nukes.

[the-pi-guy]

I can't think of any glitch that improved a game...