[impendia]

I don't see why you can't reuse whatever mechanics you like.

Return of the Obra Dinn was a 2018 mystery puzzle game, where you have to figure out how everyone died in an ill-fated voyage at sea. Amazing game.

I searched Reddit for "games like Obra Dinn", and this led me to Case of the Golden Idol, a 2022 game with similar mechanics. The developers were quite open about being inspired and influenced by Obra Dinn -- and they ended up creating something in the same genre, but very much their own creation, with their own flavor. And also very enjoyable.

Originality is nice, but I'm not at all convinced it's a prerequisite for quality.

[setr]

To further justify your position; Originality is just the unique composition of various unoriginal things. If you chase quality, originality will appear as a byproduct as you deal with the intricacies from your specific combination of features.

That is, everything interesting appears from the relationships between subjects, not the subjects themselves (the edges, not the nodes, of the graph). You could change any one major component of the game, explore it sufficiently, and you will inevitably have something sufficiently original despite 90% of the original core being duplicated — the nature of exploring the relationships thoroughly — chasing quality — will inevitably lead to a cascading series of changes until you reach the new stable point