This is not the official DreamCast Game Emulator, and no any games include.
You must get DC roms ,and use this app to play.
Cortex-A9 dualcore, 1ghz+ is the minimum hardware for decent speeds
The Dreamcast BIOS is required for this emulator to work. In the internal memory of your phone, create a folder named dc, make a folder named data inside it, and put the bios files there (dc_boot.bin, dc_flash.bin). If you are using a file manager, the path for the folder is /sdcard/dc/data/. You should dump these files from your Dreamcast, Google has many tutorials on how to.