I can think of a handful of games that, despite being games that I’ve enjoyed, never really became part of a “genre”. Do you have any like this, and if so, which?
Are they games that you’d like to see another entrant to the genre to? Would you recommend the original game as one to keep playing?
I recently got hooked on Twinkle Star Sprites, a Neo Geo versus shmup. Chaining enemies on your screen sends attacks to the opponent’s screen. Those attacks can be bounced back, and reversing a reversal can create special attacks or even a boss summon. There’s a lot going on and it’s tragic that no spiritual successor ever tried to recreate this formula.
It did get a JP-only PS2 sequel, but it looks to just be largely the same game, just with a different cast of characters and the lovely spritework replaced with a much worse low poly 3D.