Seditionis - Tower Defense is a sci-fi based infinite TD game with 190+ upgrades to make your gameplay, units, and towers more powerful.
4 tiers of towers in each line, with 20 upgrade levels each. An introductory story gives you a sense of what you're fighting for. After all, this galaxy needs you.
Your progress is auto saved every time you earn or spend perk point upgrades, purchase perks, or close the game.