A single play event called The Researchers Story (Special Edition) is coming to Metal Gear Survive next week. By participating, players will be able to unlock special items for the game, including new cassette tapes containing Silent Hill and Castlevania music, and a Pyramid Head costume, so you can run around in the game looking like the iconic enemy from Konamis famous horror series.
Source: N4G PC Dress up as Pyramid Head in upcoming Metal Gear Survive event