Cyborg 009 is based on the manga and anime of the same name, which began a long time ago. There are eight characters that you can use, but one of them is set and you can only choose two others for each mission.
The run uses 008 (Pyunma) and 005 (Geronimo) most of the time. 008 can jump forward quickly and swim in water, while 005 does heavy damage to bosses. Various power-ups are collected to level-up 009 (Joe) due to an event near the end of the game.
The run uses the easiest difficulty due to the final boss taking less time to beat.
If you play this game, it is recommended to level-up 009 first, and a lot.