No, the Riot MMO is NOT cancelled. As of December 2025, the League of Legends MMO is still in active development, though it underwent a major design reset in March 2024. Riot co-founder Marc Merrill confirmed in February 2025 that the MMO is "probably the project I personally spend the most time on" and that "the team has a great direction now and is making a lot of momentum."
However, the project has "gone dark" for several years while the team rebuilds from scratch. Don't expect any major announcements or a release date anytime soon - this is a long-term project that likely won't surface publicly until late 2026 at the earliest.