omg, you basically did wild guns ;)
I wanted to make it too, but it was way out of scope. But really cool you tried to make something like that.
Sounds were cool, the western alien mix was cool.
I enjoyed blasting the aliens away, also cool and hilarious is the dodge-roll ;) I liked the crosshair and movement.
A few more weapons and more variation in enemys would have been an improvement. I think the font is western style so it is fitting your theme but I would go for something western themed but with better readabilty.
Cool bossfight, but could not beat him. Well done!