This is a fun and addicting game. However, the mechanism had to be tweaked a bit to improve it. It's not fair that if both were standing on the same square, if the player were to attack, the opponent is unharmed, but if the opponent attack, the player dies. This is also annoying when the AI decides to stand right one square right above spiked floor.
The above mentioned mechanism also has another side effect, that is when the opponent decide to linger on the bottom square, they are invincible whilst being able to do to the player mortal damage. And when this happens, seriously... It is a huge waste of time since the AI's movement patterns are random, which means that they may stay on the bottom row for an indefinite amount of time.
The Flamethrower/Shotgun ninja has defective attacking animation. His attack showed only a square's worth of range, however it is in fact 2! Not to put into account that it has a very high initial attack speed after moving from square to square. He is in my opinion made too hard to handle.