Spare underwear at the ready.
AVP is most nerve-shredding when you're playing as a marine. The poor muscle-bound humans spend most of their time fumbling in dark corridors desperately fending off scores of fast-moving xenomorphs. As if that wasn't enough, Predators often stick their oars in - and they've got camouflage tech. Make sure to pack those flares!
Valve's co-op shooter's great when it ramps up the action to ridiculous levels, throwing hundreds of speedy Infected at you with all the subtlety of a bulldozer in a glass house. When it adds Special Infected, like the disgusting Boomer, to the mix, it's time to wave the white flag.