First, just a few random notes:
1. The map controls are only partially mapped to WASD. W and S move the selector up and down, but A and D don't do anything. Arrow keys work fine.
2. When you first arrive at the map, if the selector is over a level, you are neither told what the level is, nor can you select it, until you move the selector off it and back over it again.
3. This may just be me, but I would default to a slightly slower screen rotation rate. Brilliant idea to make this an option BTW.
4. The startup screen that says 'press any key to continue' doesn't actually take any key, only certain ones.
5. At one point during a level, I made an infinite jump. In other words, I jumped, and the jump kept going up forever. I finally figured out what was causing it:
If you pause with escape, then press 1, it exits the pause menu and botches your movement in an odd way. This can lead to rocketing into the netherworld, floating above the ground, or drifting out away from the ground at odd angles.
My experience with janking/halting:
My system is a i5 3570k, HD4000 (no dedicated gpu), 16gb ram, Win 7 x64, SSD boot drive.
When I first tried Airscape out last night, it ran perfectly. I ran at default settings, in windowed mode. I didn't see any halting or janking in the opening or during gameplay. Out of necessity, I initiated many unfortunate encounters with lasers, but to no avail. Had lots of fun, got a little seasick.
Today...my luck hasn't been so good.
Exited back to the main map. Decided to try the first level again. You know how the first level opens with sqiddster falling a long ways, and crashing into the ground? Well, for me, that intro played like a malfunctioning slide show. The delay between frames was well over 2 seconds. When sqiddster finally hit the ground, the game stuttered a bit more and cleared up. Ran around a bit, everything seemed fine. Exited, re-entered level. Falling intro was smooth as butter.
Shut the game down, rebooted it. Everything worked fine. No slideshow on level 01-01, no jerking, nothing.
Tried again. One short (0.1 sec?) lag on the falling intro to 01-01. The occasional micro-halt during gameplay. Everything else ran fine.