First of all, thanks for accepting me here at the forum. Being able to relive my childhood arcade memories is an amazing prospect.
I have been trying to play The Ocean Hunter and managed to load the ROM through the UI provided with the latest Supermodel downloadable from the forum, x86-r862.
However, I am an absolute tech lemming and cannot figure out how to make controls work in it. I've looked up tutorials here but so far have only found more complex issues such as setting up actual light guns. Clicking on the "Controls" configuration has popped up the black screen where I can assign buttons to the keyboard, but sadly I couldn't figure out how to put the mouse there.
I would like to figure out a way to make my mouse function as the gun, and hopefully have two mice at the same time to play with my brother. He's coming over for holidays and we grew up burning 1€ coins in this specific arcade.
Would anyone be so kind as to provide me with some instructions?

Thanks in advance.
PS: I can't figure out how to run it on fullscreen either but that's a minor issue.