Hello, rough rivals!

This patch introduces Steam achievements and fixes several bugs listed below:

• It is no longer necessary to complete the tutorial to start the campaign.
  
• The level-up card selected when using a mouse and keyboard is now properly displayed.
  
• The ball should no longer go out of accessible bounds and respawn at the center of the field.
  

Have fun, and see you soon for more (friendly) violence!

Coro.