Generally, multiplayer games exist so that players can co-operate. Whether it's shooting opponents or just working as a team to get the job done, it's been made clear by the popularity of multiplayer games over the years that we love working as a together.
But this doesn't mean that all multiplayers are made for wholesome cooperation. In fact, there's a metric ton of games that thrive on making you turn on your most trusted buddies - despite how absolutely diabolical this is.
It's especially diabolical when you don't see it coming though. In games that have a competitive element or are based around dishonesty you know what you're in for, but plenty of titles pull the wool over your eyes until the last second before revealing you need to murder a pal.
Sure, you might discover that one of your nearest and dearest is a remorseless savage capable of keeping a completely straight face while lying to you - but that's something that's probably better to find out via video games than real life circumstances.
In short, when the Mario Kart gets tense, trust no one; not even yourself.
10. Age Of Empires
In Age of Empire, not only will you betray your friends, but you'll betray them for four hours, after having previously teamed with them for another four.
And the betrayals are suitably brutal, too. In order to properly ally, you can sign treaties with other players, only to secretly cancel the treaty and slaughter all their troops before they've even really realised what's up.
Issue is, you'll often do this trying to preempt their betrayal, which explains your actions, but doesn't totally justify them - especially if you find out that your loyal pal actually didn't intend to stab you in the back at all.
While most of the replay value and entertainment in Age of Empires comes from learning how to optimise your forces and strategise effectively, there's also something extra special about battles against friends, because it becomes about knowing them as well.
Would your friends have your back even when it's not at an advantage to them? How long would it take them to betray you? Is there any signs or suggestions that they are about to wage war on you?
It becomes a total mind game, and as fun as this is, epic betrayals can leave you a little sore for a minute or two after you've been defeated.