Epic and People Can Fly trialled a co-op mode in Bulletstorm - but canned it after it "broke down" the key game mechanic.
That's according to Epic design chief Cliff Bleszinski, who told The Telegraph:
"First off, it was in there at one point and it actually worked, but we found that the game shifted from being this kind of puzzle shooter into essentially this downhill skiing simulator, where people were seeing how fast they could get to the bottom of the mountain.
"Really the game just broke down, and it was a situation where people would race through the game, ignoring the vistas and they wouldn't set up as many skillshots.
"So when we made the decision to go straight campaign, it gave us the chance to put in one-offs that could only be controlled by one player, like the giant robotic dinosaur, where you don't have to worry about Player 2, or slow motion one-offs that could only occur in a single player game."
Bulletstorm's campaign remains single player-only , there are co-op elements in its multiplayer modes - including Anarchy, in which up to four players take on waves of beasts.
The game's due out on Tuesday in the States and next Friday in Europe. We'll have our Bulletstorm review ready for you on Monday.