Changes since v1.3.1:
- Initialized the stack at the beginning to increase compatibility
- Fixed a bug that prevented you from destroying the directional cannons
- Added an option in the main menu (pressing '9' and '0') to switch between 50Hz and 60Hz in MSX2 and MSX2+. Moreover, if the game detects that the computer is a 60Hz one, then it sets it to 50Hz automatically if possible (only possible if the computer has a V9938 VDP or higher)
- Fixed some little issue in the code with Joystick input (not sure if it was causing bugs, but just in case)