Recently there has been a surge of homebrew clones of popular PC games to the PSP. Clones such as StarCraft, Age of Empires, Red Alert, and more. Remember, developer companies of these games still have active copyrights on their games. Ripping sprites from their games and using them in your own homebrew port is illegal, regardless of what coding of the backend is like (obviously homebew code since the source for these games has not been released yet). Also, using the game's name in your port, even with different in-game sprites, is also illegal. So you could have a clone of say StarCraft, call it StarCraft PSP, and use different sprites as well, but you would still be producing illegal material.