Thanks for checking it out, and for the detailed feedback!
The game is supposed to grab the mouse when the window is focused. but you should be able to free the mouse by pressing escape or alt-tabbing. if it doesnt work like that then theres a bug. what version of windows are you on?
Controlling the strength for bouncing is a neat idea. but would probably not work well on a controller as with a mouse, probably no issues with having it as a feature and leaving it up to the player to utilize. i think im gonna slow the the movement speed and scale down the gravity a tiny bit to make bouncing a bit easier. also experiment with visualizing bounce trajectories. having more tutorial levels might solve this issue.
i've heard similar complaint with the wall jump. the issue i wanted to bypass was accidental wall jumps. if you wanna double jump up a right wall, holding right/up and press jump the player probably didnt want to wall jump to the left but thats what would happen. holding left and pressing jump i feel makes accidental wall jumps impossible. its easy enough to add an option for though
The pause menu is a bug, but it looked cool so i kept it. will fix at some point ;P