Catrap is a platform/puzzle game where a boy and girl work through a series of 100 puzzles. This breaks a curse and returns them to human form. Completing each level involves climbing ladders and moving blocks so that each enemy can be defeated. A rewind function is present for trail+error attempts to get to the solutions. But that feature isn't needed here.
This run makes clever use of the switch mechanics. Switch can't be used immediately after defeating an enemy, so other actions are performed while the enemy falls off the screen. Attacking from the ladder is slightly faster, the author uses this and other similar tricks to help save time.