Kuhn poker is a very, very simple form of poker invented to study game theory.
This is a two-player game with one round of fixed betting with raises capped at one bet. The deck has three cards: K, Q, J. Both players post an ante of one bet. Each player recieves one card from the deck. The players may 'bet' or 'pass'. If one player bets, the opposing player must bet to stay in the game. If both players bet or both players pass, the cards are shown and the player with the highest card wins.
The opponent in this applet plays a Nash Equilibrium strategy. The means that, in the long run, you will not be able to beat it. It also means that, in the long run, it will not be able to beat you unless you play a dominated strategy.
Calling a bet with a J is an example of a dominated strategy. Making the first bet with a Q is an example of a weakly dominated strategy.
As long as you avoid dominated strategies and your opponent is playing an equilibirum strategy you will break even. However, if you are not playing an equilibrium strategy yourself then you are giving your opponent an opportunity to benefit by exploiting your strategy. But then, any strategy that exploits your non-optimal strategy is itself open to being exploited.
I am planning to expand this applet to include non-optimal and adaptive opponents.