What's a good iOS game for a quick mental break that requires precision and focus, but isn't overly complicated?

As someone who spends a significant amount of time reading and writing, I appreciate having something that allows for a brief mental shift. "Dr. Driving" offers that. The game's core mechanic is simple: drive and park efficiently. However, the challenge lies in mastering the controls and achieving high scores. It's an interesting implementation of physics in a mobile game. While the graphics aren't cutting-edge, the gameplay itself is quite compelling. I find it's a pedagogically sound way to improve focus and coordination, and the cross-platform availability means I can continue a game on my iPad after starting on my phone. It's certainly not a replacement for a real break, but it's a surprisingly effective way to clear my head between research sessions.