PPSSPP (PlayStation Portable Smartphone and Tablet) is an emulator for Android that lets you play a bunch of PlayStation Portable (PSP) games on your device at full speed. You can use your own PSP games or free homebrew games that are available online. The only requirement is that they be in .ISO or .CSO format. No other file format is supported.
The best part is that the app is completely free, although if you want to support its development you can buy the paid version instead. The list of compatible games is quite extensive, and you can even download and play .ZIP and .COD files compatible with your favorite games. That said, to enjoy them to their fullest potential, you'll need a fairly powerful Android device, as many of the emulated PSP's specs are outdated by today's standards.
With PPSSPP, you can also create your own levels using any of the available tools. You can use images from Photoshop, Gimp, or Paint.NET to make your own textures and models for the games you want to play with your Android device. And all of this from your Android device, without having to touch your computer screen at all.
PPSSPP (PlayStation Portable Smartphone & Tablet) is an excellent PSP emulator that lets you enjoy all the best titles from this console in high definition on your Android device with extra features.