BWTD (Bloons WatchTower Defense)

Bloons WatchTower Defense, due to its completely different gameplay mechanics, is a whole new game series. The main protagonist is the WatchTower, who was the monkeys' small city. The monkeys have to defend the WatchTower at all costs. However, instead of a one-dimensional track, the Bloons are now attracted to the tower on a 2D plane. Different tracks are now replaced by obstacles or buffs like Bloon speed boosts, dart shields and portals, to block or help the Bloons, depending on the difficulty of the track.

Mechanics
Bloons are attracted to the WatchTower on a 2D plane, much like dogs chasing after a stationary ball. The WatchTower has 100 HP (on Medium, by default). At first, all it can do is shoot a WatchTower pellet, one per second, and it destroys one bloon layer per shot. Thus, in very early game, the WatchTower is the main and/or only defense. However, you can upgrade the WatchTower using XP you get after completing games to get boosts that may allow the pellet to split upon impact, get further range, reduce reload time, increase damage per pellet, increase WatchTower HP or, this is the most important, make money. This not only allows you to upgrade the WatchTower in between games, but also in game to place and upgrade more defenses, like Dart Monkeys, Tack Shooters, etc. Each tower has a specific HP value too, and if a Bloon hits it (a Bloon attacks when it bumps into something) it loses HP. However, the Bloon doesn't lose any HP, even if it hits the WatchTower (except for if you upgrade body damage, which may exist for some towers). Usually, the higher the Bloon level, the more HP the tower loses. Some Bloons also have special attacks, like chain damage. The Bloons still have proportional speed and characteristics. However, the towers now have 5x HP. The upgrades are based on BTD6, including Heroes. You can have different tracks, but they only have different terrains (eg water, obstacles, bloon buffs, etc.)