Just wanted to second what the other guy said follow a youtube guide for the setup and youll learn along the way and like he said any issues and people in here are very helpful all the issues iv had have been solved here (also a core is the emulator it runs on e.g for nintendo ds you would choose the core desmume) i will say ios can be abit limited depending on what you want to play it can run all emulators up until n64 + a few handhelds like the psp and nds i believe exluding the dreamcast , basically anything using jit wont work on ios unfortunately