Games no starting on fresh OS

As title states, i went through the intro video, followed the guide on how to install the OS on new SD card. Everything went fine, all process was quite smooth. After install, I've noticed that there are no games, so i started trying to move old games from preinstalled SD card. And now not a single game boots up. It just starts the loading and then after few seconds returns to game list. Can't figure out what am I missing?