51 Okey, also known as Bloody Okey, is a board game developed by SDATB for Android devices. This game is different from other Okey games as it can be played offline, anywhere and anytime.

The gameplay of 51 Okey involves two types of hands, the Big hand, and the Normal hand. The Big hand Okey is a fake Okey, and the total number of all the Stones opened must exceed 51 to open. Otherwise, the player will be penalized with 500 points in the Normal hand and 1000 points in the Big hand. In the Normal hand, if a player opens, the numbers in their hand are added with five, whereas, in the Big hand, it is written as a penalty and multiplied by ten.

The game features an advanced artificial intelligence, fluid visuals, and different game options such as multi-fold, non-fold, and assisted or unassisted. The scoring system is unique, and there are punishments for the player who commits the tile. The game also allows playing without waiting for anyone and is free of charge. Moreover, the game can be saved on a cloud-based platform.

Overall, 51 Okey is an excellent offline board game with unique gameplay and features that can provide hours of entertainment to users.