Nicholas Prosper shot dead Juliana Falcon, 48, Kyle Prosper, 16, and 13-year-old Giselle Prosper at their home in Luton in September last year.
Wearing a yellow bucket hat and a black t-shirt Prosper said: "On June 30, my sister decided to make the incorrect choices on episode one of season one of The Walking Dead games, and for that her face will be mutilated further than necessary.".
In a series of vile videos seen by The Sun - which we have decided not to share - sick Prosper defends paedophiles and necrophilia.
"We are pleased that Prosper has pleaded guilty and will not put his family through the pain of a trial, and that he will soon face a significant jail sentence.".
Prosper said he was "chosen" to protect a fictional character called Clementine in the zombie video game, in a sign he struggled to differentiate between the real world and make-believe.
