Streets of Rage 4 (known in Japan as Bare Knuckle IV) is a 2D belt-scrolling brawler developed by DotEmu, Lizardcube, and Guard Crush Games (with porting help by Blitworks and Seaven Studio) and published digitally by DotEmu (Yooreka Studio in China) for the Xbox One, PlayStation 4, Nintendo Switch, and PC on April 30, 2020.
The fourth installment of Sega's Streets of Rage series (and released 16 years after Streets of Rage 3), Streets of Rage 4 features a new game engine (based on Guard Crush Games' previous indie game Streets of Fury) and high-definition hand-drawn graphics (similar to Lizardcube's previous game Wonder Boy: The Dragon's Trap). While most of the game plays similarly to the original trilogy, it includes new gameplay mechanics (such as an updated combo system, situational health regeneration after performing special attacks, and a new Stage-based scoring system). In addition to two-player online multiplayer, the game introduces four-player local multiplayer to the series.
Set 10 years after the fall of criminal mastermind Mr. X's syndicate, the story involves a new crime syndicate mysteriously corrupting Wood Oak City, led by Mr. X's own children (the "Y Twins", Mr. Y and Ms. Y). Joining former cops Axel Stone and Blaze Fielding in their investigation are guitarist Cherry Hunter (the daughter of their old friend Adam) and mason Flyoid Iraia (a cyborg apprentice of the scientist Dr. Zan).
The game later received a DLC expansion, known as Mr. X Nightmare, on July 15, 2021. This expansion adds new Survival and Training modes set in a holographic simulation from Dr. Zan, adding a variety of new enemies and weapons. It also adds three new playable characters, one unlockable retro character, a new ultra-hard "New Mania+" difficulty, and the addition of both alternate abilities and alternate color palettes for all characters.
The XONE, PS4, and Switch versions of the game received a physical release by Merge Games on July 30, 2020, with the PS4 and Switch versions also received a limited physical release by Limited Run. It also received a port for Google Stadia on July 15, 2021, and will receive mobile ports (by Playdigious) for iOS and Android devices on May 22, 2022.
Similar to Streets of Rage 3, only four characters are playable from the start, with additional ones being unlockable. All character appearances from Streets of Rage and Streets of Rage 2, as well as most appearances from Streets of Rage 3, are unlockable for use, each with their original pixel art graphics and original audio.
- Axel Stone is a martial artist who retired from the police force and began living an isolated life in the wilderness after the fall of Mr. X, only to be brought back to fight the new syndicate after a call from Blaze. His retro appearances (from all three original games) are unlockable.
- Blaze Fielding is a dance instructor who was dishonorably discharged from the police force sometime after the fall of Mr. X (for refusing to take anger management classes). Her habit of getting into street brawls gave her insight of a new crime syndicate. Her retro appearances (from all three original games) are unlockable.
- Cherry Hunter, daughter of decorated police officer Adam Hunter, is a guitarist who plays electro progressive rock in some of the most dangerous parts of the city. When Blaze called Adam for help against the new syndicate, Cherry went in his stead. She serves as the "agile" character of the original four, sacrificing her damage output for quick strikes and fast movement, and is the only one of the four who is able to run.
- Floyd Iraia is a mason who lost both of his arms in a horrible work accident, only to build new cybernetic ones with the help of brilliant scientist Dr. Gilbert Zan. When Blaze called Dr. Zan for help against the new syndicate, Floyd went in his stead. He serves as the "grappler" character of the original four, sacrificing his movement speed for powerful strikes and grapples.
- Adam Hunter is a police officer who became an agent with the Special Investigation Forces after the fall of Mr. X. Tasked with infiltrating crime organizations in the shadows, he waits for the right time to strike. He is unlocked after completing Stage 4, and his original SOR1 appearance is also unlockable.
- Estel Aguirre is a high-ranking police officer dutifully serving a police force corrupted by the new syndicate. She serves as a minor antagonist throughout the game's story. She is unlocked after purchasing the Mr. X Nightmare DLC.
- Max Thunder is a former professional wrestler and a good friend of Axel. His whereabouts are unknown prior to the rise of the new syndicate. He is unlocked after purchasing the Mr. X Nightmare DLC, although his original SOR2 appearance is unlockable in the base game.
- Shiva is the former right-hand man of Mr. X and is presumed to be part of the new syndicate. Mastering the art of Kenpo, he excels in both speed and power with his martial arts, but refuses to equip any weapons. He is unlocked after purchasing the Mr. X Nightmare DLC, although his SOR3 appearance is unlockable in the base game.
- Skate Hunter and Dr. Gilbert Zan are unlockable in their retro appearances (SOR2 for Skate, SOR3 for Dr. Zan). Roo, in his original SOR3 appearance, is also unlockable with a cheat code in the Mr. X Nightmare DLC.
- Operating System: Windows 7
- Processor: Intel Core 2 Duo E8400 | AMD Phenom II X4 965
- Memory: 4 GB RAM
- Graphics: NVIDIA GeForce GTS 250 | AMD Radeon HD 6670
- Storage: 8 GB available space
- Operating System: Windows 7+
- Processor: Intel i5+
- Memory: 8 GB RAM
- Graphics: NVIDIA GTX 960 / Radeon HD 5750 or better
- Storage: 10 GB available space