A game way ahead of its time; Siren basically tried to do what PT did later: A game meant to be discussed with friends and online so you could piece together progression and lore, as well as several ARG elements that deepened the lore and characters... sadly that proved to be its downfall, as the overall experience was too obtuse for most players at the time.
Beyond that, its a special game... it and its sequel having some of the most unique elderich lore out there, not falling back to the usual lovecraft mythos and instead crafting its own rich and unique setting...
And for me its special for another reason... for the longest time I had a gaming magazine with a walkthrough for it, I read it back to back over and over again, I tried to get the game multiple times, relying on the usual brazilian piracy at the time... but every copy was broken (all around the same place which makes me think it was something to do with them pirated copies) so I could never progress past a certain point... Still, I kept buying new copies of it, even brought one along for a trip during an extremely rough period of my life.
Playing and trying to figure out this game helped me a lot back then, and I still enjoy seeing other people figure out its lore or helping them do so.