A free program for Android, by Skymob Technologies.

The NES Emulator is a free, open-source software package that allows you to play many of the most popular video games on your Android phone or tablet. It is an emulator that can play games from the Nintendo Entertainment System (NES) and Super Nintendo Entertainment System (SNES) on your mobile devices. It is designed for Android devices running an OS of version 1.5 or higher. It can also be used on devices powered by an ARMv7 (Cortex family) CPU.

To use the NES Emulator, you first need to install it. You can do that by downloading it from the Google Play Store. Once installed, you can either play a game or use it as a controller.