I actually asked the author about submitting this and they said that they won't submit this TAS, because they're planning to make some more improvements to it.
Regular Show: Mordecai and Rigby in 8-bit Land is a platforming game made by Wayforward in 2013. You play as both Mordecai (who can double jump) and Rigby (who can go through small gaps). Later on you can transform Mordecai into a spaceship, suddenly changing the genre to a space shooter. Rigby can change his playstyle to that of a top-down shooter.
This is a TAS of the first world (1 of 4):
Link to videoUser movie #638721782005581500
Few things of note:
From the looks of it, you have a fixed altitude when you jump.
It's better to finish a level as Mordecai since ending with Rigby is a few frames slower.
Your horizontal momentum when you land on the ground can be halted if you hug a wall. Slightly drifting to the opposite direction in midair can slightly alleviate this issue.
I decided not to grab the powerup in the first level and instead avoid the Tough Guy enemy by slowing down near the wall (at around 0:58 in the encode).
This game seemingly has that Mega Man thing of "jumping earlier to fall down faster".
The boss is really easy. You can just keep hopping on his head constantly to skip having to wait for him to spawn a higher platform. I then carefully time the 2nd jump I still have to land the final hit at the earliest frame I can.
EDIT: Now thinking about it, maybe I can switch between characters constantly to see if I can hit the boss's head earlier a few more times. I don't know, it's worth a shot before moving on.
I think that's all I have for now... Now time to start the second world (hopefully).
From what I was able to understand, Mario stops on a dime. I never really gave acceleration much of a consideration. When you stop holding left or right, Mario stops moving horizontally seemingly instantaneously. Every time I hugged a wall, Mario stopped moving seemingly instantly. When I stopped hugging the wall, Mario continued moving forward at seemingly the same speed he normally goes forward every time. To me, personally, I didn't notice a difference in movement speed. I don't even think this game has an in depth movement system like in the official games (although I could be very wrong about that).
In this game (as well as the prequel) Mario has a fixed altitude when he jumps. More importantly, it doesn't matter how long I press the jump key, it could be 1 frame or a whole 60 frames, my altitude will always be the same every time.
Say for instance I jump from one platform to the other and they're close to each other. I have to wait to land onto the next platform despite the rather short distance. After this platform, there's a higher floor I have to jump on again and the same rules apply.
I hug the walls from time to time because I have no other choice but to wait to land on the ground.
I hope this answers your question.
Which moment are you referring to? When I jump on the Goomba, or when I hit the block with the hammer?
I'm not at home since Thursday, so I'm being slow answering questions right now.