Mighty No. 9 is a debut 2D side-scrolling action game from Keiji Inafune, known for his work on the Mega Man series. Players control Beck, the ninth in a line of powerful robots, as he navigates twelve stages. Combat involves players utilizing weapons and abilities acquired from defeated enemies, alongside Beck's unique transformations, to overcome the eight other Mighty Number robots. The core loop emphasizes skill-based platforming and aggressive combat, where chaining together combos with Beck's Absorption Dash skill is key to achieving high scores and S-Ranks.
The game's single-player campaign spans twelve distinct stages, complemented by a New Game+ mode that introduces two additional difficulty levels. Beyond the main story, players test their precision in a Single Player Challenge mode, which comprises dozens of mini-missions, and compete for best times in a dedicated Boss Rush Mode. Multiplayer options include a 2 Player Online Race Battle, where competitors race head-to-head through stages, and a 2 Player Online Co-Op Challenge Mode, requiring cooperative use of Beck and his partner Call's distinct powers across multiple missions. An optional chiptune soundtrack, composed by veterans like Manami Matsumae, Takeshi Tateishi, and Ippo Yamada, provides an alternative audio experience. Mighty No. 9 delivers a modern iteration of classic 2D action platforming, built around skill mastery and diverse gameplay modes.