If they are cheap games from Hong Kong, then they are most likely pirated games (illegal copies.) I've seen a few of them and I have one from the Philippines. The saving feature doesn't work very well, and the game software knows it's pirated. The game sometimes told me to play it on "official hardware." The game was Dragon Ball Z: Transformation, and it also had Loopy's NES emulator with 254 NES games. A friend of mine had a pirated version of Mario Kart and it stopped working after a while. Be careful when buying cartridge-based games, especially Gameboy, Gameboy Advance, and I've seen some pirated Game Gear cartridges as well.