Ya... it's hit/miss on which games have the issue. MAME so far. Never had issues with NES games yet. Probably another way around it for sure, but, no keyboard hooked up. Usually start/select together exits, sometimes it just ignores the one button completely and keeps adding coins.

When I make the game console, I plan to add a button to run a shutdown command on the console (not the joystick). Bought a small momentary power switch with a small LED in it, add a resistor and connect to the GPIO's directly. I bought a pack of these and jumper wires as well, for a small guitar amp project with a breadboard, figured sacrifice a few to get the single-pin parts so no soldering to the Pi directly. Though in most cases I'll probably run the shutdown from RetroPie's shutdown screen.

I have a master power switch going in the rear as well, because still need a way to power off the powered USB hub which will power the joysticks and the cooling fan.

Media server is running an old Core2Quad I upgraded from. Was running Win7 for years, but decided to change the case, switch to a fanless GPU, and got a free 32GB SSD drive so, decided to try OpenElec. I have 2 x 3TB drives in the computer as well, and a few computers stream from it in the house, all wired with ethernet, no WiFi. Runs fine... and if I ever need to switch out the other HTPCs, I'll probably use a RaspPi. But, for the main server HTPC on my TV, I'll probably always run a full computer.... though next upgrade, I'm building a case and getting a mini/micro ATX. Looks nice right now, but the new case is noisy, flimsy, and interior layout could be better. I can build something much nicer and more silent... probably for less too. Silverstone Grandia GD09, for the price, very disappointed, but after lots of work, got the noise down and installed a Flirc, internal edition not USB, added a small iR window at the front, can't tell it's there. Works pretty good, pretty impressed with OpenElec... again, tried Ubuntu, installed it twice and still wouldn't even update properly because of repository issues and such... unimpressed.