Oklahoma Gin online is much closer to standard gin rummy than Kalooki. it uses the standard deck, and is limited to two players.
The biggest difference is "knocking." When the first card is turned over after dealing, the point value on that card is the "knock" value – so 10 or face card is 10 points, A is 1 point. Turns contain only a draw and a discard – no laying down cards.
When a player has runs in his hand that, if laid down, leave card points equal to or below the knock points, he can knock. Knocking is when each player puts down all his runs and the hand ends.
A couple more things happen in the knock. First, each player is allowed to add cards to the other player's runs. But, if the knocker "goes gin" and puts down all the cards in his hand as runs, the other player is not allowed to play on his runs, and is stuck with those points. Moreover, the player who went gin gets 20 bonus points, and the opponent gets to score no points at all.
Second, points are determined by the difference between the opponent's cards and the player's cards. If the player, at the end of all the card play, has a higher point value than his opponent, he loses that difference to the opponent. If he has a lower value, he is awarded the point difference.
Oklahoma Gin Rummy Game play then continues with a new hand, and play goes on until one player reaches 100 points.