10 Times Video Games Made You Betray Your Friends
3. Castle Crashers
You could easily play a decent portion of Castle Crashers under the impression that the entire game is just wholesome co-op from wall to wall. It's you and your pal (or pals) against countless swarms of evil, and that builds a bond that feels indestructible.
Well. It's indestructible until you finish any of the boss battles, and discover that - if more than one of you has made it to the end alive - you now need to duke it out in order to win the reward of a smooch from the princess.
Despite the fact that none of you are planning a future with this cartoon lady, you will suddenly viciously turn on each for little reason other than because you can, fighting tooth and nail to prove that you're the best of the team.
Hilariously, because the boss battle are at the end of stages, you'll continue this almost as a cycle - building your bond back up again as you fight through levels, only to beat ten bells out of one another whenever you're given the chance.