A. It's my first game so I'm not sure what it means :p Is it about optimization? I know that I put way too much wall objects so I'll have to clean this for the next version. Maybe I could've made it all smaller given the quality of my graphics but I know so little about graphics for the moment and I'll dig into it further for my next game
B: I think it covers all the screen's height. But in the next version I'll try putting the clouds in the background and adding parallax (or at least reduce their opacity if I can't make it work :p)
C: will do ;)
Thanks for your remarks. Very helpful :)