weekend player
A person(s) and/or game who plays or is played in a casual manner.
...Nah, Josh isn't good enough for our GameBattles team; He's such a weekend player.
or
...Nah, I'm tired of Black Ops, lets play something weekender-er, like Uno.
or
...Nah, I'm tired of Black Ops, lets play something weekender-er, like Uno.