end of the tour, the band moved to Los Angeles, California, to restart production, this time with collaborator Rich Costey, who co-produced Absolution and Black Holes and Revelations. Rather than concentrating on the album as a whole, as they had on previous albums, Muse focused on recording and mixing one track at a time. The band hoped this would improve the individual quality of the songs, and they worked with no particular theme in mind, even halfway through its production. One of the first tracks produced with Costey was "Thought Contagion", based on a bassline and theremin melody conceived by Bellamy. The band began recording it in November, and replaced the theremin with a ten-layer vocal chorus performed by Bellamy and bassist Chris Wolstenholme. The verses were originally intended to be supported by a heavier, arena-style drum sequence, before experimentation with programming led to a trap-inspired drum sound that emulated the Roland TR-808. The folk rock-inspired track "Something Human" was also co-produced with Costey. Shellback and Timbaland also co-produced tracks. Artwork The album cover for Simulation Theory was designed by British visual artist Kyle Lambert, who had worked on Netflix’s television series Stranger Things. It was created using Procreate on an iPad Pro with Apple Pencil, and features a retro style focused on 1980s aesthetics, prompting comparisons by critics to Lambert's earlier work and similar aesthetics used in both 1980s and contemporary media. The cover for the "super deluxe" version was designed by Paul Shipper, who had designed the Dolby Cinema posters for Walt Disney Studios Motion Pictures films such as Star Wars: The Last Jedi and Avengers: Infinity War. It features an array of characters, including members of the band, in a stylistic arrangement similar to Shipper's previous work. Promotion In April 2017, Muse shared footage from their early studio sessions on social media, with captions teasing new material "coming soon". More cryptic teasers were published in the weeks following. The first product of the sessions, "Dig Down", was released on 18 May 2017, along with a music video. The song became the opening song on the band's 2017 North American tour. After the band's return to the studio, Muse teased "Thought Contagion" as their next release, and teased several more tracks to follow. "Thought Contagion" was released on 15 February 2018 with its accompanying music video. Muse continued to post in-studio footage on social media in the weeks