Everything got now ported over to libgdx and it runs faster and better than ever! (If you ever want to code for android, you should give it a try!)
I can now deploy it on the PC and on the device and that speeds things up a lot.
Also, I decided I should stop re-inventing the wheel - so I dropped my own level-editor and switched to Tiled as my editor of choice.
Since there was already a compiler in place for my old editor, writing a new one only took a day - yay!
And - to keep the post interesting - here's a screenshot of the "game":
(Note: all the art was done by me
