Elevators - Yes elevators, again
It's an old request but maybe a new method for solving an old problem. Instead of physically moving the avatar, why not just beam him (or her now) to the new floor by simply changing the player location.
The elevator would need two kinds of blocks: an entry/exit block and then an extender for floors that have no exit.
The functionality would be akin to the sliding door. The player could open and close the door. A panel button inside the elevator would control the functionality. The door would close and the player would disappear from the world grid. A drop down menu of all entry block names would appear. The player would select the entry block desired and press go. A cool-down period of one second per 2.5 meters of travel. The player would then appear inside the destination block desired. Once the door is opened, the player would reappear in the world matrix.
Elevator blocks would have no external windows, the only view would be inside of the entry block. So there would be no moving parts or actual movement of the avatar. It would simply disappear and then reappear.
Elevators are something that would greatly enhance immersion. Using a jetpack on a planet or in a large spaceship doesn't quite get it. Ladders seemed a little convoluted as the avatar has to move along the ladder and then somehow enter and exit the ladder system without falling down it. A system that simply "teleports" the avatar to a new block would have less impact on game mechanics and seems technically easier. There already is a mechanic to teleport the player around as "Space Master" so the rules around the elevator would be the only strain.... such as limiting the use of the elevator to one player at a time.