Castelian is a puzzle platformer in which the basic gameplay is to discover the route necessary to ascend towers from bases to apex.
Per the story in the game manual (see below), your frog-like character is tasked with demolishing these towers by planting a bomb at each tower's top (wouldn't bombs around the bottom be easier?). This game was also released on multiple other systems under one of the following names: Nebulus, Kyorochan Land, Subline, and Tower Toppler. Apparently the story varies slightly on the different releases.
The only actions your character can do are to move around the tower horizontally, jump, and shoot little white balls to break flashing ledges or kill enemies (though most enemies are invulnerable to this attack).
Story (from the manual)
JUST ANOTHER DAY IN JEMMERVILLE
You're witnessing a typical sparkling, summer morning in downtown Jemmerville. Both suns have risen over the planet Centrus, where summer, of course, is the only season. And it is here, on the island's precious gem-deposits are talked about throughout the Triangulum galaxy, and they're the envy of almost every life-form in this corner of the universe.
Julius was asleep in his terraineum when the holographic intercom sprayed out its message. It was the president of Domoloco and Sons inc.:
"Julius we have a serious situation. The governor has reported that 7 alien towers have surrounded the island. If one more appears, the island will be completely enclosed. The naviports are almost cut off. The hyperfreighters are trapped... nothing is getting in or out. I've given the governor my personal promise that Domoloco and Sons would handle these towers... No one knows what they are or where they came from but I want them demolished! Now that's not too difficult a mission, is it?"
Julius slowly opened his eyes and found that the president's personal hologram - not the one of his secretary - was still activated:
"Wake up, Julius, and topple that tower!"
As Julius started to say something, the hologram began to dissolve as quickly as it had appeared.
- The game was fairly straightforward to TAS. Any delay in motion was intentional to either avoid an enemy or manipulate their spawn point.
- Two game settings are changed in this video.
- The game is played on the more difficult mode (HERO) instead of the default (NOVICE).
- Interestingly you can only play the game with EITHER sound effects or music. For this video I chose music. However no desync will occur if the 'Select' input at frame 153 is cleared; thus playing the video with sound effects instead.
- What appears to be arbitrary jumps are usually present to avoid stepping or landing on a platform that would otherwise disappear, causing a fall.
- Bonus levels - in which you are supposed to collect gems for points - are ended as quickly as possible by either enemy strike or falling in a hole.
- Occasionally an enemy strike on a tower is necessary to make progress or to facilitate reaching a desired location easier. Usually the enemy hit is the one shaped kind of like a molecule.
- There are a TON of lag frames where input is not read and relatively few places to minimize lag.
- The final input is the 'up' press that enters the door at the top of the last tower.
EDIT: Submission withdrawn. I was pointed to a youtube video of the Japanese version that was faster, apparently due to using different routes. I'll tweak my video as necessary and re-submit with a (hopefully) faster time.