>>714455884 (OP)SotN. The best thing about castleroids is exploration. SotN has it.
Hollow Knight. It also has exploration and a lot of locations are connected to 3 others at least. Also, by completing ~2.5 zones, 2 bosses, getting dash upgrade and wall climb upgrade (half of the third zone, not even bossfight guards it) you get access to most zones in the game, getting lantern allows you to navigate those few with darkness (which is also possible to do without lantern, but is rather frustrating).
Rabi-Ribi. Nice to see, nice to explore, nice to hear, weird interesting plot with various implications. Only thing i don't really like is bullet hell, but after a few dozen attempts on most bosses on normal it is manageable.
Castlevania HoD - mostly for aestetic and atmosphere. It is SotN 0.85 from the point of view of a human in the mysterious lair of horrors rather than of a half-vampire son of the owner of the castle coming home to solve a mystery.
Separately are Shantae games - RRevenge and SS, also mostly for aestetics. Absolutely beautiful forest in RR.
Also there is Blasphemous and The Last Faith. First looks better in terms of quality and uniqueness, second (being a mix of Blasphemous and Bloodborne gameplaywise and getting plot advancement moments and visuals from the latter) just feels better as a game, despite being "actually linear".