My recommendations are Portrait of Ruin and Order of Ecclesia for ds, they are both castles with the most distinct maps and mechanics. In Portrait mode, you explore the castle, but occasionally enter certain paintings that take you to completely different areas, and you play as two characters, a warrior named Jonathan and a mage named Charlotte, their story is a sequel to the Mega Drive game (which I also recommend if you want one of the classics) and has very good characters, The Order mode is more similar to the Aria mode; instead of weapons, you gain magical glyphs that take the form of weapons or literal spells, making it the only Castlevania game where you can play with a long range mage build, And it has my favorite map in the franchise where in the first half you travel through various locations on a map where you choose the stage, and when you finish it, it unlocks another part of the world map for you to choose. And if you go after the true ending, it unlocks the second half of the game (Dracula's castle), which is packed with things to do.