Touhou Luna Nights is a metroidvania developed by Vaka Game Magazine and Team Ladybug and published by Why so serious? and PLAYISM in 2019 on PC. After constructing a parallel version of Gensokyo as a playground, the vampire Remilia seals her maid Sakuya there for fun. Sakuya, hellbent on doing her chores for the day, plays along and explores the fake Gensokyo while under a spell that supresses her powers.
Being a Touhou game, the story of Luna Nights isn't more involved than a bunch of cute girls with a frightening amount of magical power fighting over dumb stuff. As such, there really isn't much to latch onto in the story (especially if you aren't familiar with the characters). It's a game with next to no fat, so every cutscene has a distinct purpose, be it to explain a mechanic or introduce a boss. This is good for the pacing, but takes away chances to give the characters unique flourish beyond their aesthetics.
Those are good aesthetics mind you, as the sprite-work is excellent and the effects used for boss fights are unique to every boss. That, coupled with every area having its own (often Castlevania-inspired) look really sells the visuals. The music is no slouch either, featuring a bunch of remixes of character themes from past games redone to awesome results.
The reason for picking Sakuya as the protagonist is that her ability to stop time and throw an endless amount of knives makes for some really interesting mechanics in a metroidvania. Throwing knives costs MP which slowly regenerates. Sakuya also has access to a bunch of sub-weapons (Read: Just different kinds of knives and the like) that cost a lot more MP to use. As a nod to the series' roots, you can graze close to enemies and their projectiles in order to regenerate HP, MP and time.
Time is of course spent to stop time, but you can also slow down time for free for a few seconds. In the frozen time, a bunch of things happen. Normal enemies are of course frozen still, but Sakuya changes a bit too. The grazing distance increases, letting you basically absorb MP and time from surrounding enemies for free, while making sure you can't graze those same things in realtime or slow-motion to regenerate health.
Knives thrown while time is stopped pile up and are limited to the amount of knife upgrades you've aquired so far. But they do not cost MP and instead deduct from your time gauge. Same thing happens when you move in frozen time. This sound somewhat unbalanced, but all of these systems interact in a wonderful fashion, especially during the game's awesome bosses.
The first thing you need to realize is that MP and time is essentially the same resource (i.e. ammo), though time is important as a defensive measure as well. While in realtime, you can output more damage consistently thanks to Sakuya's sub-weapons and the heightened effect of grazing while doing so. But MP regenerates slowly and you can easily burn through your supply. At that point, you need to stop time at the right time to absorb MP, catch a break and then retaliate with a burst of knives, blowing through your supply of time and restarting the process until your time gauge refills.
What really elavates the combat here are the late-game bosses designed to screw with your ability to stop time. They have attacks that activate when you stop time and screen nukes that can really screw you over if time isn't moving. So it's vital that you adapt to their pattern and know when to slow down time, stop it or just let it be in order to evade, regen HP and get in position to destroy boss projectiles and get in some damage. It's really fun, though the extra boss has a ridiculous amount of HP.
Just like the story, the exploration elements are very minimalistic. The game's levels can only be entered sequentially, so there isn't really any sequence breaking to be done. But you still get the metroidvania experience of unlocking new abilities (Read: Even more knives) and using them to backtrack to find power-ups and the way forward. It is a tad linear for my tastes, but the various obstacles and enemies that change properties during frozen time (or ignore it altogether) keps things engaging.
One last thing of interest is the gem system, which lets you pick between selling them to get a few extra of the standard upgrades (more time or knives) and some restoration items versus keeping them for minimal buffs that can't be found elsewhere, like faster MP recovery and a bit of extra defense and attack. I did playthroughs testing both ways of using gems, and the results weren't that different, but if you feel more confident having more time on the clock instead of regenerating MP a bit faster, then the option is there for you.