In Immortal Defense, the protagonist gives up his body and becomes an immortal, disembodied entity in order to protect his planet. The game follows his progress over a very long time, and the player confronts questions about whether it was a good idea to give up everything he had. The gameplay is in the 'tower defense' subgenre, the player places artifacts representing his will on a path, and has to place them strategically in order to defend his people.

• Over 15 hours of real-time strategy "tower defense" gameplay.
• One-hundred core stages and fifty custom optional stages.
• A psychological, character-driven storyline written by an accomplished writer.
• Eleven types of towers, with seven upgrade levels each, balanced and useful for different situations, each based on a different emotion.
• Level editor for extendability and customization.
• 10 different difficulty levels, for those whose strategic skills vary.
• An original soundtrack with over 40 minutes of music. Also available as a free download.