Streets of Rage 4 DLC Mr. X Nightmare, free update announced for 2021 - Polygon

Streets of Rage 4’s Mr. X Nightmare DLC will add new characters (including former boss Estel Aguirre), a new survival mode, and new moves for existing characters. A free update is also coming with new difficulty options.

Streets of Rage 4 - Mr. X Nightmare DLC : How to Unlock Roo and Clown Wars Achievement

Streets of Rage 4 (and Mr. X Nightmare DLC) - New free update bringing more than 300 improvements

Dominic's Indie Picks Of 2021. A bad year for Earth, a great year for…, by Dominic Tarason

Streets of Rage 4 DLC 'Mr. X Nightmare' and free update announced; downloads top 2.5 million - Gematsu

Streets of Rage 4 - Mr X Nightmare DLC -- Is it worth it?

Updated Re-release - TV Tropes

Dominic's Indie Picks Of 2021. A bad year for Earth, a great year for…, by Dominic Tarason

Co-Optimus - News - Max Returns in First Streets of Rage 4 'Mr. X Nightmare' DLC Footage

Streets of Rage 4 (2020), Switch eShop Game