Sonic Madness is a 2D side-scrolling platformer fan game that features a unique character-swapping loop across a multi-act campaign structure. Instead of controlling traditional heroes, players directly command Dr. Robotnik and Metal Sonic, with gameplay split into distinct character-specific acts that require completely different navigation mechanics. When controlling Metal Sonic, gameplay focuses on momentum-based speed, utilizing precise jumps, traditional spin-dashes, and sudden high-speed horizontal dashes to eliminate environmental hazards and enemies. Conversely, acts featuring Dr. Robotnik transition the gameplay into a methodical, physics-based aerial platformer. Players use a limited-use jetpack mechanic to hover, bypass vertical obstacles, and position themselves during complex boss encounters against rival robotic units. The game includes custom 2D pixel-art menus, traditional checkpoint systems, classic ring-collection loops, specialized underwater sections, and distinctly themed levels including "Star Brain Zone" and "Funk Surgery Zone."