[Ascovel]

I played the original Half-Life 2 mod which this is (as I understand) a direct recreation with better visuals and audio.

Judging by the mod it's nothing like an adventure game and hardly a game at all. Instead think of The Path, but with a lesser amount of meaningful interaction possibilities (in fact nothing that isn't provided by the Source engine by default).

You could describe Dear Esther as the hearing of an eerie poem within a beautiful 3D location (a misty, rocky island full of caves).