This game I released recently is done with improved version of Polish Letter Worlds engine. Main changes are in Luigi physics as well as removing "sticky roof" problem. Nevertheless since this engine is still under test phase, please make sure to report any bugs/strange things occurred durning your gameplay. Be mindful about save system thing. It should work fine but if you notice any strange problems, please write down about that as well. This will help me a lot in developing Minus Worlds 2.0 with this engine.
If there will be need, I might prepare fixed version of this small release. There's a chance I might add to this game another bonus level or maybe something more hehe
I found a bug with Luigi. I think you have originally set luigis jump higher than that of mario. But the problem occurs when we purchase Lui suit from the market after selecting Luigi. Already he jumps high, and after having lui suit, he jumps much much higher than expected (moon jumping) almost going above screen for 2-3 seconds. However, on selecting Mario, it jumps normally. I think this is important as the bug continues even if we enter the main game. Players may take disadvantage of this bug and thus skip levels. I have made a short video of bug to show exactly what I am saying.
-Luigi is literally walking on ice, it's nearly impossible to control him
I think Luigi jumps better than Mario. So Mario has better controls than Luigi by purpose. Otherwise, it would be biased and all would take Luigi. By this, I think you have a choice between better controls (mario) and better jumping (luigi).