~5 Minutes to finish one Stage , I'm assuming it's the same every Stage.
I feel like the Shotgun could use a visual overhaul, to make it appear more Holy, like the Pistols.
I'm not particularly a Fan of the Gravity forcing me towards the Center of the Level/the closes Face/whatever it does, often Times I thought I should be able to jumpdash to a Pillar and run around there, just to be pulled into the Center again. Then one Time I somehow enter inside of a Pillar, and got into a Place with a Ton of Demons in it, just to pop out extremely far off from the Level itself and descending upwards towards it. No Idea if that was Intentional or not, it felt weird, but the entire Game feels weird due to the Gravity.
The Shooting Gameplay works for what you want I think, but you need better Stages and more Demon Variety instead of just floating towards you I guess.
Personally I don't like timed Stuff like that, and prefer it if it was an Arena-shooter along the Lines of Doom or similar, with locking you in a Room until a certain goal is met, be it surviving a given Time, killing enough Demons or similar then opening the Door for you to move along in the Level, with some Story of the Nun having to clear Hell or whatever. But I understand that that's not the kind of Game you're going for here.
The Gunplay itself starts of too slow I think, but at the End it evolves/devolves into too many Enemies just swarming you, blocking movement, so I just held down Fire until the Time ran out. Maybe ramp it up faster, but not as high, theres some balancing to be done there. Also depends on Amount of Content, if you have just the one Arena and the 2 Weapon choices and 1 Enemy as it is currently, then maybe you don't need to twiddle it as much, but if you're adding multiple Enemies and Arenas, aswell as more Weapons, ideally to unlock upon reaching Milestones, to incentivize playing through Stuff again and again to unlock it, maybe more.
As it stands right now I think the Gameplay is pretty much where you want it to be, and what it is missing is a lot of Content.
Menues could use a bit of work, there's not a lot of them, thats fine, and they're not bad by any means, they're just a bit spread out I think. But maybe that's due to the missing Content aswell.
Artstyle needs better Enemies. Thats the main point there, the Guns are fine (apart from the above mentioned suggested rework for the Shotgun look), the Interface could maybe be changed a bit, the Guns are too big/high up on the Screen for me, and the Level is rather empty looking, but that's minor points compared to just one floating Cone with a Head as the Enemy.
With some overall Polish, and then more and more Content, Enemy Variety, Gun Options, Level Selections, and so on, it could be a fun Highscore Shooter for the right Players I think.