Backstab Gaming Protocols is a PvP variant of Invisible, Inc. which can be played either between two players as a one-shot game, or in a knockout tournament format. The rules can be found here.
Backstab Gaming Protocols was invented in 2021 in order to run a tournament celebrating the 6th anniversary of Invisible, Inc.'s release. The tournament was played between May 8th and May 17th, 2021, with six players participating:
The tournament was hosted by Andrew Kay and streamed live. Recordings of the games can be found on YouTube.