After experimenting a bit, I have figured out how to play so far js tetris, js pacman, and js snake. Pacman worked the best. on pacman i was in overview mode, and when i held down R and pressed up, down, left, right, pacman did too!. but when i didnt hold down R and pressed d-pad, the top zoomed in screen moved, so i can follow my pacman with top screen while i play, or i can look at bottom, which shows pacman a bit smaller but still playable! Its a bit slow but thats ok it was fun. I got pretty far before the ghosts got me :D
no its not technically a site, its games in java script meant for PC but is possible to play on Opera browser (DSi) it seems some games are not possible because of keys like ctrl and stuff but some are possible.