I've just bought the game and for a fact I know from Mandalore's review that you can shoot with the mouse by tinkering with some files but I... don't really know what to do you guys know a way?

Necrobumping with the solution for others

1/ Open the autoexec.cfg file in shogo's folder with your favorite text editor
2/ Find lines similar to

rangebind "##keyboard" "##[SOME NUMBER]" 0.000000 0.000000 "Fire"
and replace it with
rangebind "##mouse" "Button 0" 0.000000 0.000000 "Fire"

(while you're at it, do the same for doublejump)
rangebind "##mouse" "Button 1" 0.000000 0.000000 "DoubleJump"


Or you can also edit those options from the menu :
Options -> Mouse -> First button / Second button , etc