Tower Defense games have been big this year, probably reaching their purest peak with PopCap's Plants Vs Zombies. Combine the basic defense idea with fantasy and MMORPGs (Massively multiplayer online Role playing games), and you get League of Legends, a multiplayer online strategy game.

With an isometric view, League of Legends is played online in two teams of five. Each team has a base, surrounded by a lots of protective turrets. Outside that area is the opposing team's area. Every player controls a Champion, of which there are various kinds. These are supported by spawning minions who accompany players on their journeys, and take most of the damage too. League of Legends is controlled via keyboard and mouse and is pretty simple, although there are lots of spells and special attacks for you to utilize during the game, which make it more complex.

The aim of League of Legends is to battle through enemy minions, destroying enough defense turrets to create a path to the enemy 'ancient'. Once that is destroyed, you win the game. Sounds simple enough! However, while it's simple to pick up, and addictive too, games of League of Legends take a long time.

The defense turrets aren't easy to destroy, even without enemy attackers, so it's an achievement to manage one. The more you play, the more experience you gain, which gives you access to more spells and strength, which make all the difference in a game. If your team is a little weaker then defeat may feel certain, even though it takes ages!

League of Legends looks good, with an attractive yet clear style, similar to World of Warcraft (but not in 3D). The sound is well done and really professional, making League of Legends a fantastic free game, one of the most polished you will play.

League of Legends is a compelling multiplayer Tower Defense game, but can eat up hours of your life if you're not careful!