Robo Defense is a compelling Tower Defense-style action game where you must assemble a protective battalion of robots to keep out enemy invaders.

The object of RoboDefense is to stop the armies of invaders moving from their base on the left-hand side of the screen, to your fortress. In order to do this you have to buy robots using the money you accumulate from killing enemy robots.

Each robot in Robo Defense has a different kind of weapon, and its potency generally depends on how much you paid for it. Once you've bought a robot you need to make the important decision as to where to place it. Look carefully at the route the enemy forces are taking through your defenses to get an idea of the areas you need to strengthen.

Robo Defense is an engrossing game that will have you hooked for hours. The game includes 'reward points' that are given out for good performance during play, and these can be used to power up the weapons. There's also an 'Achievements' section where you strive to make certain goals. There are 10 levels of difficulty in this free version of Robo Defense, but only one basic map.

It's a shame there's no two-player mode but, overall, Robo Defense makes for an entertaining way to spend a bus journey.