One of the few good mobile games in the 2020s, and one of the best tower defenses out there- and still has constant updates. Been playing for about 2 1/2 years with only one complaint: Auto-redeploy not always being consistent. However, I can look past it with how many characters, modes, mechanics and lore/story the game has. It'll take years to run out of things to do. Warning though, early-game you will miss out on a lot of things due to not being strong enough or having enough resources saved

This game is a gacha tower defense game. The gacha rates are decent you get free pulls frequently. The game is fun and has more depth than your average tower defense game. The challenge level is consistently difficult, forcing you to think on your feet and try new tactics. There is enough content that you won't ever run out. Overall this game is excellent. Sets the bar for gacha games. Edit: 5 years later, the game is still top notch. It's easier than ever for new players jump in.

I've played for 5 years straight and the replay value just keeps increasing as time goes on. New players have a glut of content to play through, with dozens of sidestories outside of main, and veterans have a good number of endgame modes, the permant rogue lite mode and its variants in particular. There's also a permanent base building/survival mode. Other modes are also available seasonally like Contigency contract, the new multiplayer Ice Breakers, the boss rush Trials of Navigator, etc.