You will get the gun in upcoming levels, and what skip level key ;) Besides its useful for accessing certain levels. In the final version it will be taken out.

Thanks!, When you set the acceleration that high, the force is great enough to press the box completely against the wall, and then all the forces are directed horizontal, so the box can't spring back easily.

Yeah, I'm well aware of this, and the new version fixes this and a lot more. It will be uploaded as soon as i can fix a few more of the bugs.

Yes yes, i am aware of all these bugs and working to fix them. It seems i caused more problems by rewriting the physics engine than i fixed.