Blood was Monolith Production's first game, and it certainly made a great first impression back in 1997. Blood is also regarded as the third game in the Holy Trinity of Build Engine games, and for good reason. The gameplay is fun, challenging, exploration is rewarded, and just like Duke Nukem 3D and Shadow Warrior, parts of the levels can be blown up to either reveal secrets, shortcuts, or simple process through a level. The game was fantastic back in 1997, and it's still brilliant today.
Nightdive Studios are known for bringing classic games to the modern era, and Blood: Fresh Supply is no exception. The Devs have use their own KEX engine to add new features to Blood, such as higher resolutions, Vulknan, DirectX 11, and OpenGL 4.2 support, improved online multiplayer, including co-op, and more. If you haven't played Blood yet, it's your duty as a gamer to play it.