Hitting a nice multiplier chain and getting 300+ bullets to shoot is crazy fun.
I like the card thingies you can use strategically to block your opponents from gaining territory and to bomb/pierce through. The upgrade system is also a nice way to add some variability to a purely rng game.
Got destroyed on my first round but managed to obliterate the enemy with large multipliers on my second game.
Would've loved to see some more Doki references, besides the little dragoons on the slots machine and her gun. Maybe in the bonus cards or as decoration / sound effects.
Overall, good job!