Several really fun and interesting new mechanics, those being the new reward multiplier thing when collecting items, and the special weapons for each character. All of the weapons feel very different from eachother and bring entirely different ways to play with them. (For Marisa however the only different way to play is not playing, her unique weapon kinda sucks sadly. MarisaC from MoF was not missed.) Playable Sakuya is always really good for bonus points too, thanks ZUN. Fun bosses, interesting themes, and a return to independent incidents. Overall, a very fun game.
Primordial Beat~Pristine Beat is one of my favorite themes for the series, really damn good and love the percussion for once, definitely a standout for the soundtrack of this game. I know I said fun bosses but god I couldn't go without talking about Seija. Flips your damn screen and shoves you in a washing machine. The fight is a bit scary but it's still honestly pretty fun and is very unique, out of the large pool of unique stage 5 bossfights.

This is it. This is the hardest touhou game. Not because it's particularly difficult perse, but because of pure bullshit. Shou Toramaru I don't care how kinda cool you are, can suck a fat one because of that fight. And the unique mechanic of this game? Shitty little UFOs you have to babysit and possibly get yourself killed for.
On another note, this game has some neat fights and themes. Also it brings back the old life and bomb system but slightly changed, so that's pretty nice. Emotional Skyscraper is tied for one of my favorite themes in the series too, this shit is godly. Also playable Sanae is pretty cool.
The only game I will never be able to 1CC.

Tied for my favorite touhou game. Absolutely love the soundtrack, bosses are challenging, debatably my favorite cast, and for once, the story actually correlates with another directly. Has a shot type system kinda similar to the tag system of Imperishable Night, which nicely expands on some characters while introducing others. One of the harder games, yet with a fair compensation of easier to obtain lives, and the revamped continue system(for better or worse). If I'm ever bored and looking for a challenge, this is always one of my first stops. (Also Okuu supremacy, gotta love the nuclear bird wife. Solar Sect of Mystic Wisdom~Nuclear Fusion is probably my favorite theme in the series too it go so hard.)