Regicide is a human tabletop game played across the Imperium of Man. It uses a board and pieces or can be played using a virtual holographic display. It is similar to the ancient Terran game of chess, and can be played on a "hooded" board where only certain pieces are visible, making the game more complex. It is known that this game was played by Chief Librarian Petrok of the Iron Snakes Space Marines Chapter as a trainee Librarian to improve his tactical ability without relying on his psychic talents.
During the Orkish invasion under the Beast, Second Captain Koorland of the Imperial Fists Chapter played against Tech-priest Phaeton Laurentis thirty-eight times, losing every match in the process due to Laurentis' cybernetically-augmented cognitive processors.