If you don't know DoTA, von, then you're way too old

. Go back to playing Doom you slowly decomposing corpse of what was once a man!
Same to you Rice.
Basically, DoTA started out as a map/mod for Warcraft 3. On this map, there are 2 sides(good guys and bad guys) and 3 lanes. Both sides spawn "creeps" at regular intervals that go and try and kill the enemy base. Seeing as both sides are mirror-balanced, neither side actually pushes forth - it's an endless cycle.
That's where the players - the heroes come in. They fight the creeps, and the other heroes, to break through the lanes and eventually kill the enemy base. When they fight, they also gain experience and gold. With gold you buy items, with experience you level up (duh), with the maximum level being level 25.
There are also neutral creeps all around the map which you can kill for some extra gold and exp.
The game is very much about teamwork - if you run out on your own, you'll be easily ganked by 2 or 3 enemy heroes, giving them very large boosts to both gold and experience.... So doing that is unadvised.
The game is played from a top-down perspective(it WAS originally made in WC3), and the not-so-recently released Demigod was based entirely on DoTA as far as the idea goes. Personally, playing both games, I believe HoN to be quite more fun, no matter how good Demigod was

.