Ja, it has to be GB or GBC for it to work { there is a pokemon GBC rom out there somewhere...I have one that works perfectly fine on my Sansa e280 v1} . I would love to play GBA games on my sansa e280, but alas, I cannot.
What they need to do is make a NES emulator and name it RockNES NES games are the best =P
Make sure you have a separate folder for your GB /GBC games . I have mine named Games and is the 3rd file when I click on Files. If the game does not open when you click on it, hold the middle button and go to open with and then rockboy.
- If ya have any more questions about rockboy I could help you =P