Thanks for playing! Originally space bar was used instead of middle click (and it still can be used, it just isn't mentioned anywhere), but some people like to use arrow keys and space is quite far on the keyboard from there. Therefore I changed it so that everything is on the mouse.
Also, this is my first Godot game, and I've never played with exporting for the web, but yeah might look at how to do a web build after the jam. Thanks for the feedback!