Okey as you know it, penalties as you don't. Lay off a tile on your opponent's meld and the penalty is theirs. The okey's color sets the hand's penalty; whoever can't open pays.
Open a private table and drop the link in your group chat. The game starts when four players sit down. Nobody around? Join a quick game, or play bots offline.
Slap Okey is coming soon to iPhone, iPad and Android. Free.