Ouendan duology and its international counterpart, Elite Beat Agents, which contains the same gameplay but had its characters and themes adapted to fit a Western audience.
In all three games, players take control of a small 3-person team of skilled dancers who use the power of song and dance to aid people who specifically call for their help in overcoming their problems by raising their morale.
Doing so successfully grants small boosts to a constantly declining health meter, representing the effectiveness of the dance team in helping the person in trouble, with the amount depending on the timing of each target hit.
The amount of health remaining also affects whether or not the person being helped is able to improve their situation at the end of each phase, with the ensuing outcome being represented as a cutscene on the top screen, which will also in turn affect the mission's ending if it is completed successfully by finishing the performance without allowing the health bar to reach zero for mission failure.
Based on ideas by iNiS founder Keiichi Yano and drawing upon a setlist of J-pop songs, it follows the efforts of a ōendan in Yuhi Town in Tokyo, Japan to use their cheering and dance skills to help people in need throughout the larger city.
Following the success of Ouendan, iNiS developed an spiritual sequel to the game based on a new intellectual property that caters to an international audience, releasing it in 2006 outside of Japan as Elite Beat Agents.
Combining this knowledge with his adoption of the invigorating mentality of ōendan to improve his company's flagging morale after Gitaroo's unexpected commercial failure, his development team then put together what would become Osu!
[1] Upon release in 2005 exclusively in Japan, the game drew praise and interest from import gamers, leading iNiS to consider localizing the game for non-Japanese players, before ultimately deciding on coming up with a new intellectual property that retains Ouendan's gameplay, with a different setlist, premise, scenarios and characters that are geared towards a more American audience.
[12] Yano also expressed interest in making a sequel to Elite Beat Agents in an interview one decade after its release, but remarked that it could only happen if Nintendo had another system like the DS that would suit its unique design.