Ok, now I can play it. :) I made a small change though to do that. In the player.gd line 25, i changed it to: if get_viewport().get_mouse_pos().x < scr_size.width/2:
The game looks really nice and you made very good use of the theme! It's kinda hard to control though. I think a variable run speed (maybe with mouse pos distance to the player) would be nice.