Rktcr is tool-assisted-speed-run: the game.
It both requires and enables you to play perfectly.
It is a very difficult game.

Rktcr (from “rocket car”, pronounced /ɹktkɹ/) is a physics-based side-view action-platformer-turned-puzzle-platformer; that is, it’s an action game meant to be played thoughtfully at much slower than real-time.
Rktcr is. Players can see the future and control the flow of time, allowing them to play frame-perfectly. Paths through levels can be easily shared, for boasting or collaboration.
Rktcr contains 37 challenge levels, ranging from easy to impossible; and 31 world levels, algorithmically arranged into 300 worlds of varying complexity. All told, there are more than 1600 paths to discover and optimize.
The Steam release of Rktcr adds Achievements, Trading Cards, and a smattering of graphical polish.