Secrets of the Five-O AI

I’ve noticed a few App Store reviews lately claiming that the “Hard” Computer opponent in Five-O simply draws better tiles. In other words, the deck is stacked in order to increase the difficulty for the player. I wanted to set the record straight, and since Apple doesn’t have a way for developers to respond directly to reviews, I’m responding here. To all those concerned, the AI in Five-O does not “cheat” in any way. The games are not rigged and the algorithm that chooses where the computer should play does not take into account the tiles in the player’s hand, the tiles that will be drawn next, or any other information that wouldn’t be available to a human player.

The AI algorithm in Five-O is actually not that complicated. The computer looks at the tiles in its hand, and then it does an exhaustive search where it tries placing every combination of its tiles in every possible horizontal and vertical sequence on the board, starting from the top left corner and working down and to the right. Each time the computer tries a new combination, it checks to see if it is a valid play, and if it is valid, it calculates the score and records it in a list of all the possible plays that it could make. After listing all the possible plays, the “Hard” AI simply chooses the one that scores the most points. The “Easy” and “Medium” AI’s choose a random play from the lower and middle parts of the list, respectively.

So how can you beat an AI that always chooses the highest scoring play? Well, one way would be to get lucky with the tiles you draw. But, there are also some strategies you can use to improve your win percentage. The computer doesn’t check to see if the play it’s going to make will open up a high scoring play for you. So, you should try to always take advantage of those 3x and +10 bonus squares, and be careful not to leave them open for the computer. Some other general strategies are to play your sequences so that the tiles on the ends are low numbers, or if a sequence contains two tiles with the same number, put those next to each other. Pairing numbers makes it harder for your opponent to play a sequence running parallel to yours, and capping sequences with lower numbers makes those types of plays less valuable.

Those are just a few of the strategies I’ve come up with. I’m sure you can come up with more!