BTD4 features improved graphics, loads of new and original tower types and tons of upgrades for each tower type. Heaps of tracks, save games, career mode, sandbox mode and apopalypse mode. Bloons Tower Defense 4 will give you almost unlimited replay value.
Also included is optional MochiCoins premium content featuring lots of extra tracks and special booster upgrades like double boomerangs, exploding darts, and double cash!
Saved games require a MochiGames login - it's free and trustworthy, we know the Mochi guys well. The pay-for content is completely optional and extra and is not required to enjoy the game as we intended it.
Enjoy!