That's an endless, right? 21 minutes in, got to 2662 canceled bullets before I got stucc to the ice block that covered The Last One Standing™ and ultimately lost the game in the most helpless way I've seen in the last 10 months.
"Hold until Marisa and Sakuya come to help you!" -Game page. In the end help never came :(
Anyway, the game flow feels quite complete actually.
It's just about balance tweaks now - It's kinda hard at the beginning, then the barricade/speed related upgrades make things easy and passive, and then it suddenly spikes way up when the danmaku-like attacks come in and destroys everything at once. Even on a second try where I know what to invest in and where I scramble to plug the holes in the fire and ice as fast as I can, near-extinction occured - and there was one.
Looks like the attack patterns are a big loop of 8 minutes. So I got stuck at the end of the second loop.
Nevertheless it's fun enough~