Ad supported games is a new concept for mobile phone games. Those games are free (and also legal !!!) because they are supported by advertising sponsors.

When you play this kind of games (ad supported games), you will typically see one or two ads when you launch the game and then more when you quit. Generally, nothing is shown during the game to disrupt game play.

"So, i have to pay something to play this games?". You will have to pay only the wap traffic when the ads will be downloaded (typically 20-25Kb per connection). But if you have unlimited wap (internet) you don't have to pay.