UnoDos

UnoDos is a low-poly 3D puzzle game where you control two characters simultaneously. One responds to the left side of the keyboard. The other, to the right. They don't share a brain. You do.

Both advance through the same scenario, but with independent movements. It seems simple until both need to do different things at the same time.

Motor coordination: The game doesn't test your reflexes. It tests how your brain processes two simultaneous pieces of information. At some point, you'll stop. Look at the screen. And realize you need to think about both sides before moving either one. It's not instinct. It's planning.
Minimalism: Platforms. Doors. Levers. Buttons. That's it. No inventory, no upgrades, no skill tree. The complexity arises from what happens when these four elements meet and what your brain does when it needs to manage both sides at the same time.
Challenge: The difficulty doesn't come from enemies or timers. It comes from execution. Each level uses new mechanics and combines them with previous ones. You only advance when you understand. And when you understand, you still need to execute, with both of them.