As Left 4 Dead 2 turns 10, we speak to its creators about the Valve game that won't die

When you get to the end of a hard-fought round in Left 4 Dead 2, you're usually crawling towards a rugged red door. Maybe there's only two of your zombie-slaying quartet left... your health bars stripped away by the horde, your eyesight drained of colour, signalling that one more knockdown equals permadeath. If you're lucky, you push through the pain and make it into the safe room on borrowed time, grab some ammo and shoot the charging zombies to carve a safe route for the rest of your team.

That's unless you're playing Funny Doors. Funny Doors dictates that if you get into the safe room before a fellow survivor, in spite of earning those precious 25 points for letting them live to see the next round, you must hammer the E button to open and close the safe room door as they approach, turning the final moments of each round into one hilarious test of strength.

Left 4 Dead 2's safe room doors have a serious heft to them, and as such, each swing animation creates a tiny window of opportunity for the survivor to get past your self-flagellating trap as they howl at you on comms. Usually, they'll get pummeled by a charger and you'll have to head out and save them. It's an evil habit. Barbaric, you could say, but it's one of many peculiar bits of communal context that have ensured this game has become a weekly inevitability where many modern titles have failed to hold our attention.

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