Speed, accuracy and evasion
I've spent more time playing Resogun than anything else on my PlayStation 4, and with pretty good reason. As a rather deep arcade shooter, it enjoys a high degree of challenge and scoring potential that makes it easy to return to again and again.
The biggest criticism I have is that Resogun does a rather poor job of explaining how its mechanics come together in a scoring sense. Lacking any kind of direct tutorial, you're left to try and divine strategies from loading screen tooltips. All well and good if you have the patience for it, but if you need a primer on how to play Resogun well, the above video lays out a variety of tips and strategies for scoring over 100 million points in the game's median difficulty.