I THINK this has been brought up a long time ago(not sure), but if it is hell I'm bringing it up again!
You you know you game. You start each reply with You know you, and just continue it with something else.
EXAMPLE:
You know you play too much prophunt when you attack an apple IRL.

You know you play too much stranded when you try to plant a tree and expect it to grow in 2 mins

You know you snipe too much in TF2 when you try to keep a good line of sight to someone far away IRL.

You know you play Gmod too much when you begin thinking "The Physics gun would be very useful here".

You know you know too much when the FBI knocks on your door

AAAAAAAAAAAAAAAAAAAAAAAAAAAAC

You know you play too much Spy when you try to cloak as Scout

You know you play too much soldier when you try to rocket jump with a shotgun.

You know you play too much TF2 if you creep round corners because you think there might be a sentry on the other side.

You know you play TF2 way too much when you try to find an engineerer so you can sap his sentry

You know you spend too long on a computer when you do something stupid and your brain thinks "ctrl + z"

You know when you've been on Aprilon too much when you start posting random posts and making random threads.

Spoiler: Show

Ocfoooos!

Ohai Theer.
Now excuse me if i'm interrupting "teatime" i'll just wait outside while you- *boom*

you know you are making a good point there

You know you have pissed someone off when they drop a JDAM on you.

You know you've played too much Minecraft when you see the world in blocks and think you see Creepers in the distance...
Else you've just gone mad