The most useless button in a game.

[KaiRai]

The "Fire weapon" button on Vampire Rain.

 

[oppp7]

My favorite be the Battlefield Bad Company's picture button. Or, the instant lag button. Guess why me 'n me matey's be callin' it that...

 

[Jack and Calumon]

In a game, the taunt button in DMC4. Never noticed it doing a thing, guess it doesn't.
In General, Scroll Lock. What the hell does it do?

 

[Allstar309]

The Back button on Xbox 360. Never pressed it once.

Fallout 3 used it for the wait feature. Play fallout 3 great game.

Oh yeah. Forgot about the wait feature in Fallout 3. But I don't really use it often anyway.

You use the wait button alot in Oblivion, but I never used it in Fallout 3. I just realised that.

 

[Draco Kaiser]

The Select Button on PS2.

It was rare that any game ever gave it a purpose.

What I would say.

 

[Charley]

Tab in Warhammer Online... I see no value in targeting the second-nearest enemy to me that I can't hit because I'm not facing them, although I hold it against shoddy development, rather than the ket itself.