Liar's Dice is a fun and easy bluffing game. Once you get the hang of it, it should be easy to beat the computer at it (unless they improve the AI in a future update).
The idea of the game is that all players roll 5 dice secretly (to start with). Each player then takes turns making claims about how many dice currently have a particular number showing. Each subsequent claim/bid must be higher than the previous one. The bids are ranked first by the number of dice, and secondly by the number on the dice. So "one 3" will beat the bid of "one 2"...but if you wanted to bid 1s over top of the "one 2" bid you would have to go to at least the 2 level and say "two 1s".
As the bidding escalates, at some point you will either have to bid higher than what you know is on the table (your dice), or decide to call the other player's bluff. As soon as someone calls a bluff (or calls "spot on", which the CPU never does), the dice are revealed and either the person who called the bluff loses a dice or the person who made the bid loses a dice, depending on who is right. The guessing becomes much easier as the number of dice dwindle down, especially if you manage to keep more of yours.
The "spot on" call can come in handy when you don't dare bid any higher, but you think the current bid is actually correct. When playing with more than one adversary, it comes with the added benefit that all opponents must discard a die if you are right. If you're dead wrong, you just lose the one die as usual.