First move the "apps" directory provided in the download to the root on the SD-card. Then move your Jazz Jackrabbit datafiles to the "/apps/OpenJazz" folder. If you don't have the data-files a shareware version which contains episode 1 is available for free.
Jazz Jackrabbit is a platform game produced by Epic MegaGames.
The game features six episodes; each episode consists of three worlds, with two levels and a boss level. Jazz has a life bar; when enemies shoot or come in contact with him, he loses health that must be replenished by collecting carrots. If his health falls to zero, Jazz turns to ash and the level restarts from the last checkpoint. Also, instead of jumping on enemies Jazz must shoot his enemies with a blue gun he always carries. A variety of different bullet types can be found in the game and do varying amounts of damage.