Hi there! Thanks for your kind words, this was definitely out of our comfort zone but we learned a lot making it (using Godot for the first time + networking for multiplayer).
We haven't had time to implement a settings menu yet, but will! The platform desync was a bug we realised just after submitting the jam version, and can fix easily in an update.
As for the laser, to fire it you just have to hold down the left mouse button. It charges and then fires after a few seconds - the crosshair changes colour and there's a sound to accompany the charging. We will have a think about how to tutorialise this, and would love to hear your thoughts if you decide to have another go, playing a match all the way through.
Thanks again, let us know if you want to arrange a 1v1 against one of us!