Launch your Android emulators (Genymotion and AVDs) via Spotlight: ⌘ + Space
This is the Android port of an NES emulator written in Go.
Android Game Boy Emulator written in Java.
ScummVM is a program which allows you to run certain classic graphical point-and-click adventure games, provided you already have their data files.
Currently there are libretro implementations for systems such as SNES, NES, GBA, GB/GBC, Genesis, and even arcade games (Final Burn Alpha).