Thanks for your feedback.
Usually on microcontrollers I use uint8_t, uint16_t, uint 32_t and so on to know exactly the size of my variables. I admit it is currently a bit chaotic, I have to factorize my code, it is a big mess. For the time being I'm focused on making other games. I'm working on something like this: posting.php?mode=reply&f=17&t=3668
I also would like to make something like this: http://www.ticalc.org/archives/files/fi ... /8206.html
But this one requires more work since there is level design work to do.
Anyway, I will look at optimization at some point.