Thanks Lexxy. I'm still working on the next version which will have a series of puzzles. Hopefully the mouse problem is fixed as well, although I'm not able to reproduce the bug. :)
If it helps at all, I'm using Windows 10 Home 64-bit, playing in windowed mode, on a dual monitor setup.
Edit: I just tested it in full-screen and the mouse still leaves the game window as well.
That's great info. Thanks again!