Every month new video games are released. And every time there is huge hype around titles from the big publishers. The whole gaming world talks about them and is eager to buy and play them even before the release date is announced. But many times the games do not keep what was promised during the pre-launch. Hot features everyone was talking about are now to be found. You go to the website and find out that the feature was dropped.
The only way to prevent this frustration is "try before you buy". Do not listen to the hype! Wait until the game is released and download the official demo version before you go out and spend your money on what might not be what you expected. If you are disappointed, do not buy the game and let the publisher know the reason why. That's why they put together those demos in the first place.
There are many download sites out there, but how do you know which ones you can trust? You do not. If you want to be secure of viruses just go to the publisher's website and try to find the official demo version there. This has two benefits: First of all, you can be sure you get the most recent version. Second, there will not be viruses!
How can you be sure? Because the publishers do not want to cause harm to their potential customers. They would ruin their reputation. The publishers want their customers to have fun, but because the market is rough they often find themselves in situations where they have to drop features and release the games as soon as possible to beat their competition.
So, how can you get those demo versions to run on your PSP? Let me say that you can not do this if you upgraded your system. You will need the old 1.5 version of the operating system on your PSP. There are ways to downgrade again but that is not as trivial as it sounds.