I can't express my love for Rabbit and Steel more clearly than writing a glowing review for it. This game seems scientifically engineered to target several things that I enjoy and find addicting.

I have a secret love for a certain series of bullet hell doujin games (you probably know what I'm talking about) that Rabbit and Steel calls upon for inspiration. In addition to that, it also lends elements from rogue-lites and coop raiding mechanics similar to FFXIV, and it merges these mechanics together seamlessly.

From a mechanics overview, it's structured like a rogue-lite. You pick a cute character with a specific loadout, you hop into a run, and you gain ability upgrades and items that subtly change how you approach your rotation as you become more powerful. There's even a little DPS notification that flies over your head after a boss just so you can brag to your friends about how well you've optimized your kit. There are a few "routes" you can take to the final boss, the first of which is determined when you start. Everything after that is random until the final section. There's also a cute little story that unfolds with added dialogue and illustrated stills as you go through repeat playthroughs.

This game also really shines with coop as some of the boss mechanics are entirely different between a 1, 2, 3, or 4-person playthrough. You'll have to think hard about what that random tether you have does in the split second you have to decide where to stand. The layers of mechanics will give you a feeling of multitasking akin to patting your head and rubbing your belly as you try to survive with your limited health pool while dps'ing. This is especially pronounced at harder difficulties.

There are also hidden characters/loadouts to unlock and alternate color palettes, most of which can be unlocked simply by beating more bosses, though some are locked behind hard mode achievements. Shout outs to the shockingly few people with the adept skins for beating hard mode, apparently.

My only gripe with this game is that I have to bully my friends into buying a copy to play coop, and that also requires having 2-3 friends who also enjoy getting their teeth kicked in playing an admittedly niche genre. I look forward to the renewed interest in this game once the DLC releases additional characters, bosses, and rewards.

Oh, and don't forget to pat the shopkeeper's head. She's doing her best out there.

tl;dr:
Cute girls doing rogue-lite things with bullet hell and pseudo-mmo raid mechanics. A fun solo or coop romp if you like those things, and a dastardly way to torture your friends if they don't.