Outhold

Outhold combines tower defense with permanent upgrades earned across repeated attempts. Start a run, defend against approaching enemies, and spend collected resources on improvements before trying again. Its upgrade tree lets you concentrate power in one tower or distribute investment across combinations whose effects reinforce each other. Upgrades can be refunded without a fee, so an unsuccessful approach becomes a chance to rearrange your build. Progress depends on recognizing which purchases make the greatest difference and using them to push farther. Minimalist visuals keep attention on these experiments. The iOS version is designed for iPhone and requires an A12 Bionic chip or later.