Sonic Battle HD Deluxe Edition is a fan-made project built using the M.U.G.E.N engine
Engine:
The game utilizes the M.U.G.E.N engine , a flexible platform for 2D fighting games, allowing for complex move sets and custom character additions.
The true genius of the Sonic Battle HD Deluxe Edition mods exclusive program is that these mods aren't siloed. You can run "Era of Chaos" and "Shuffle Noir" simultaneously for a rain-slicked, time-shifting battle where Gamma's summoned E-12 drone suddenly becomes a Classic-era chibi robot that spin-dashes. The mod launcher includes a "Stability Forge"—a tool that automatically patches mod conflicts using SEGA's official API.