Unpopular games you feel are the Apex of a genre

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Great thread, and while my personal best TPS ever is RE4, Vanquish is still fantastic and one of my favourite PS3/360 games.

For me, Fatal Frame Mask of the Lunar Eclipse the pinnacle of the horror genre.
Hardly anyone played it as it was exclusive to Japan (though it's finally getting a global remake this March) but it's creeping dread, thick atmosphere, melancholy mood and slow burn pacing made it an amazing experience for me.