I've played many tower defence games since the first flash games, and BTD6 is by far the most fun and comprehensive one of them all. Massive map pool, great variety of game modes, weekly challenges, co-op, fun and diverse list of towers, and loads of synergies and strategies to discover.

It is also one of the most simple by design. It purely focuses on tower synergy, placement, and abilities rather than enemy path shaping that other TD games can do (e.g. Defense Grid). On harder maps and modes, build orders become more important depending on the sort of strategy and end goal you are aiming for. That doesn't mean there is only one way to beat map, it's quite the opposite. It means you have to be smart with your economy, tower placement, and upgrades on harder challenges and maps. The game has cross-platform saves which very handy when you want to play on the go (granted you have to buy it on mobile too).
Overall, this edition of Bloons TD has the most to offer, and is also one of the best Tower Defence games on the market. It gets a major update roughly every quarter of the year, so always new content.

I've played many tower defence games since the first flash games, and BTD6 is by far the most fun and comprehensive one of them all. Massive map pool, great variety of game modes, weekly challenges, co-op, fun and diverse list of towers, and loads of synergies and strategies to discover. It is also one of the most simple by design. It purely focuses on tower synergy, placement, and abilities rather than enemy path shaping that other TD games can do (e.g. Defense Grid). On harder maps and modes, build orders become more important depending on the sort of strategy and end goal you are aiming for. That doesn't mean there is only one way to beat map, it's quite the opposite. It means you have to be smart with your economy, tower placement, and upgrades on harder challenges and maps. The game has cross-platform saves which very handy when you want to play on the go (granted you have to buy it on mobile too). Overall, this edition of Bloons TD has the most to offer, and is also one of the best Tower Defence games on the market. It gets a major update roughly every quarter of the year, so always new content.