Its Maze of Kings for the Sega Naomi. I think.
I don't think it is. No skeletons in cowboy hats in Maze of Kings.
It also used goofy staffs instead of guns.
Even though it could have been stuck in another cab with regular light guns,
if you look at the cowboy looking dude in front of the monster on the left, he's carrying a revolver.
The characters in Maze of Kings carry magical staffs.
(I originally thought it was a 4 armed monster, but there's a cowboy in front of him)
Pretty sure this is something newer that isn't emulated yet (or it would be on my cab).
It looks pretty cool.