I liked the concept a lot, and I enjoyed my time with it. Once I got the hang of some things it was an enjoyable challenge I only got up to 680 though.

I had two problems with the presentation though that kept tripping me up. I agree with the choice to restrict the mouse movement to not be directly under the player, but having it not place an object when my cursor was over there would trip me up. I'm not sure if it was intended or not, but I think it should still place the object, just at the furthest horizontal point allowed. When trying to react quickly I would go a pixel or two over and miss placing the platform.

I also would have preferred if instead of a cursor with an icon, I had a sort of ghost image that told me exactly where the platform would be placed. Often I would place the jump platform either a little too low or a little too high, because I couldn't tell where it was going to spawn.

I really liked the physics dots showing the trajectory of the player. That was helpful and a really cool effect. Once I got a bit better at predicting where platforms would end up, it was also fun to manage placing platforms and right clicking on the enemy squares.

Cool game! I think it will be more convenient if player can change platform type by just scrolling up or down, not only scroll up for jump pad and scroll down for normal platform type.