Immortal Defense may be one of the most emotionally impactful tower defense games out there, and many have never even played it. Originally launched in 2007, it has finally arrived on Steam.
The story-based campaign features 100 levels wherein players must defend by using their emotional states (fear, pride, anxiety, etc). New for the Steam release are features such as widescreen support, Steam Workshop Support for the level editor, Steam Achievements which grant in-game perks, multiple translations, Trading Cards, and more.
Players with any interest in the tower defense genre should definitely look into Immortal Defense. The game is available with a launch week discount of $8.99 on Steam. Those who purchased a copy before can email the developer to request a key.