Jumpy was made in 2017 back when I was a very amateur programmer. As such the physics depended on the refresh rate of the monitor, and were just pretty janky in general. I've tried to correct for that as best I can using "delta time" but the physics are still not 1-to-1 with the original 60hz edition (namely, with higher refresh rates, you jump higher and have much less horizontal damping). This makes the gameplay different (easier?) from the original so I would recommend playing the game on a computer with only 60hz monitors for authenticity.