Very nice looking little demo! Ironically I'm having the opposite problem of kakoeimon, controls work fine in melonds but I just get a white screen on boot on my DSi XL with an r4. Still very cool to see.
Do you have something like startup settings on R4? I'm using twilight menu++ on SD and I also had a white screen. I enabled direct boot in the game startup settings and enabled dsi mode, after that the game started working. Other homebrew apps don't run without these settings either.
