Roblox has said that a performance of Bruno Mars’s new single in the platform’s user-created Steal A Brainrot mode attracted 12.8 million concurrent users, which it described as a “single artist record for most-watched virtual concert” on the platform. The activation issued custom “Brunito Marsito” brainrot collectibles to attendees, who accumulated a total of 5,428,644 of them.

Mars performed new single “I Just Might” and previous hit “Locked Out of Heaven” in the Steal a Brainrot game, although using standard Roblox character design and animation rather than the custom motion capture used for Lil Nas X’s performance on the platform back in 2020.

The performance was watched by 10 million livestream users in 14 countries and generated 53 million social video views, the company said. The total concurrent user count comes in below a claimed 14.3 million concurrent users for free-to-play rival Fortnite’s last major music activation, the Eminem/Snoop/JuiceWrld/Ice Spice event in 2024.

Last year Mars appeared as a performer in Fortnite Festival, the 2023 Harmonix-produced rhythm game, which enables players to perform licenced songs in a similar style to the company’s previous Rock Band titles. It has featured many recent touring acts including Billie Eilish, The Weeknd and Sabrina Carpenter.

Roblox had previously signed a deal with Sony Music to feature the label’s artists. The platform recently rolled out mandatory age checks for all users of in-game chat, following persistent criticism about children being exposed to disturbing material on the platform.