Heartbeat

Heartbeat is a demon level by Krazyman50, AncientAnubis, and AirSwipe. It is known for weird gameplay, mashing, some tight spaces, memorization, and timings. It is generally considered an Insane Demon.

Gameplay
The level starts with a slow cube with a bunch of two-spike jumps. Then there is a mashing cube part where the player must miss one of the orbs to go to the next part. This is followed by a mini cube with a bunch of mashing and tricks. Then there is a memory cube part with rows of moving orbs, followed by a tricky timing-based mini cube. Then there is a section with many tricky orb configurations with many gravity portals. Then there is a ball part with a lot of memorization and timings. This is followed by a similar dual ball segment. Then there is an easier ball part followed by a cube part with a single orb. Then there is a difficult UFO part that involves many tight timings as well as tricky gravity portals and orb usage. At the end, there is a part with lots of UFO spam. Then there is a slow cube, leading into a very long wave spam section. This is followed by a rather difficult ship section with many orbs and tricks to avoid. Then there is a rather difficult robot part with many tricky jumps. Then there is a rather long cube part with lots of memorization. At the end of this, the level ends with Krazyman's name and the two decorators, Anubis and AirSwipe.

Trivia

 * This level was made just before Krazyman50 took a break.
 * This level has a fake secret way that takes you to 99% and kills you.