RetroArch - RetroArch is a frontend for emulators, game engines and media players.
Lucky Patcher - Lucky Patcher is a great Android tool to remove ads, modify apps permissions, backup/restore apps, bypass premium applications license verification, and more.
mGBA - mGBA is an open source emulator of the Game Boy Advance. The goals are speed and accuracy.
Creehack - Creehack is an application that can hack any game for the Android platform and let you enjoy all of its paid premium features for free.
DeSmuME - DeSmuME is a freeware emulator for the NDS roms & Nintendo DS Lite games created by YopYop156.
Cheat Engine - Cheat Engine is an open source memory scanner/hex editor/debugger for Windows.