Been trying to play it on Linux, the right stick for shooting doesn't seem to be very reliable, e.g. if I rotate the stick around then bullets occasionally fly out left or right but merely pointing the stick in a direction doesn't seem to fire. Not sure if I'm misunderstanding a mechanic or if this is a bug (Stadia controller via USB on Arch btw).
So the firing is 8 way, not fully analogue, but it should be picking the "closest" of the 8 directions, regardless of which way the stick is pointing. So that does sound like a bug.
But... it's probably not something that I'll be able to fix. The binary's getting on for 5 years old, so anything could have changed, and I'd have to push it through several versions of Unity AND move to a new version of InControl... And... Ugh.
It is working on the Steam Deck, which points to either InControl not liking the Stadia controller, or something else under the hood. I don't have a Stadia controller, either, so I can't really offer much help at this point.
Apologies :/ :(