It seems the platform behavior doesn't work like this but rather moves the sprite in a triangular shape (with a smooth top).
Are you using jump sustain? Does it still do that with no jump sustain?
[quote:2ip2r4yn]I also noticed something a bit unnerving which might be a bug. i tried several times jumping in the exact same position and each time reached different heights, though with very small variations. is there a simple way to fix this like setting the Y velocity to 0 when landing?
The platform behavior is framerate independent (lookup TimeDelta on the wiki), which is important to make your game run at the same speed no matter what someone's refresh rate is. This means there are small random variations in the movement, but it shouldn't be significant. How big is your sprite? It should only be noticable with small sprites.
If it's really that important to you (although I feel a game should not be designed so specifically as to have a tiny variation crucial to the gameplay) then you can go framerate-dependent and have a fixed timedelta. That comes with all the pitfalls of framerate-dependent games though, basically for it to be fair you're going to have to turn off V-sync and have a tearing display.