Turtle Rock's Back 4 Blood is a more complex Left 4 Dead spiritual

Original Left 4 Dead developer Turtle Rock evolves the zombie shooter with Back 4 Blood, a four-player co-op action game that includes player progression, perk cards, and new strains of zombies.

Back 4 Blood is the Left 4 Dead 3 We've Been Waiting For - Easy Allies : r/Games

Back 4 Blood won't get new content as its developers focus on making next game : r/gamernews

Invaders Was A Planned Left 4 Dead Spiritual Successor

Back 4 Blood Review

Turtle Rock's Back 4 Blood is a more complex Left 4 Dead spiritual sequel - Polygon

Back4Blood Preview: The Good, The Bad, and The Ugly

Back 4 Blood Final Expansion Review: River of Blood - Magnetic Magazine

More is Better? Co-op Classic 'Left 4 Dead 2' Turns Ten - Bloody Disgusting

Back4Blood Preview: The Good, The Bad, and The Ugly

More is Better? Co-op Classic 'Left 4 Dead 2' Turns Ten - Bloody Disgusting

Turtle Rock Studios Announce Back 4 Blood - IGN