I am deep into World of Warcraft: Forever right now, currently levelling a Dwarf Paladin. It's the first time I've played the game since I was a teenager, and I am thoroughly enjoying it, although there are times when travelling gets a little... boring. As I write this, I am travelling from Ironforge to Stormwind on the back of a gryphon, twiddling my thumbs, so when I saw this new piece of software release, I just had to share it with you, because we've been writing about emulators for over 7 years here at Retro Dodo!
It's called MekkaBoy; it's an add-on for WoW Forever. There is nothing to install besides the add-on folders and nothing running outside the game. It installs into your WoW Forever "addons" folder and installs a GBA emulator inside of your game that can be opened by typing /mb or pressing the little GAME BOY button on your minimap, which opens up a fully fledged emulator with buttons that are mapped to your WASD keys.
From the get-go, there are already some pre-installed AI-developed games, themed around World Of Warcraft, such as "City Gates", "Deadmines Hold'em" and more, but in all honesty they're pretty terrible, hence why I have been using this to play some of my favourite GBA Pokémon ROM hacks inside of WoW while I wait for the next tram or when flying long-distances on the back of a Grpyhon.
Setup is very easy, and their website allows you to convert a .GB, .GBC or .GBA ROM into a MekkaBoy folder that you can click and drag into your add-ons folder; the only complicated part is that you also have to download the ROM's music files and sound effects too, which MekkaBoy does, but their download time is well over 15+ minutes for a Pokémon game, so I had to wait a while before I had a fully functioning folder/game that can play inside of WoW: Forever.

Once installed, it's pretty seamless. It works anywhere in the open world, so you can meet a friend at the inn and offer to trade thanks to the built-in multiplayer feature that connects with WoW: Forever, allowing you to trade or battle someone by typing /mb link <name>. In Pokémon Emerald, FireRed and LeafGreen you can skip the rooms: /mb trade or /mb battle opens the trade or battle right where you both stand, after you each see the other's team: nicknames, levels, held items and types. Target another player and a small MekkaBoy mark above their portrait tells you they have it; click it to see their team card and link from there. Every game that links is on their Tested page.
You can even go as far as seeing other trainers walking around your own copy of a Pokémon game. When you first install MekkaBoy, it asks how you want to play, and other MekkaBoy players on your realm who are in the same game and on the same map show up in yours, names over their heads if you choose to play "openly" or with your "friends list only". To add a friend by name, type /mb together <name>. Walk up to a trainer and press A: in Emerald, FireRed and LeafGreen you're offered a trade or a battle right there; in Red through Crystal you're offered a link, then you meet at the Cable Club in a Pokémon Center.

So, while you wait for things to happen in World of Warcraft (which is fairly often), you can enjoy your favourite GAME BOY games directly inside of WoW, which is crazy to see and makes me a very happy man! And now, it doesn't go against Blizzard's rules. It is a normal addon written against the addon API, the same way a bag addon or a map addon is. It's worth noting that this piece of software has been co-developed with AI assistance. So please do your own due diligence when downloading this!