SotC is still worth playing even if spoiled - for me it's about the overarching feeling through the entire experience that is really special. Very lonely and isolating but beautiful and tragic.

ICO I tried to replay recently but found it too clunky, but that's probably because I don't often play retro games so don't have the feel for them anymore. I did love it when I played it decades ago though.

Also, definitely add The Last Guardian to this list. It's incredibly unique, and I absolutely loved the aspects of it that frustrate some people - just try to think of it like you're trying to communicate with an actual animal, not a game.