Alpha Gamer

A person whose decisions are peak performance and whose actions are the only course that should ever be taken when it comes to the realm of games. An Alpha Gamer will obviously play the game for every member of his team, over-rule their opinions at every opportunity and bring any game to a screeching alt until his original, superior plan is carried out.

"Dude, why does this guy move my pawn, hold my cards and tell me exactly what I should do and when ?"
"He's an Alpha Gamer, might as well be playing on his own."