I'm about to become one of those "you should hack your 3ds" guys about using Launchbox for arcade emulation. All I wanted to do was play metal slug and I instead found out it's possible to play literally every arcade game ever made in high quality and awesome emulation for like. 0 effort. Easiest emulator setup I've ever done. I was always so scared of MAME, the arcade emulator, because of the whole "command line only" thing, but this actually removed all of that and made the whole thing Just Work.
God I love when software Just Works
the hardest part is finding the mythical 70 gig collection of Every Arcade Rom for MAME, but if you know how to find torrents you can. once you have that you literally just point launchbox at it, hit Go, and then it sets everything up for you. It's so sick.