Talk about a long wait, right? It's been 40 years since the original The Legend of Zelda game released on the NES, and while I wasn't born in 1986, I've spent a lot of time in my life since taking it in turns to play this game with friends. One of us would lose hearts or complete a level, and then the other would have a go. You know the drill.
Now, however, there's a ROM by Deric Miller hack that adds two-player co-operative gameplay to the original adventure. It's called Z for 2, which I suppose tells you everything you need to know about the hack! It's been created by rdlm and allows either player to pick up an item or select an active item independently. Health and other resources are shared. You can also switch an active item without going into the inventory, which is a nice touch.

One player plays as Link, while the other player uses Shadow Link. It's a great idea that adds some extra excitement to the original adventure. I mean, 'It's dangerous to go alone' is literally the message that we were taught from playing Zelda in the first place, so it makes sense that we can take a friend with us now!
That friend might regret coming, however, as there's also a new 1v1 deathmatch mode. Here's how to access it according to Deric:
To unlock, enter ARENA as your player name. Each round features a randomized set of items for Link and his Shadow to fight with. The item screen shows the items, then either player can press start to begin the round. Pausing is deactivated during the battle; the Select button switches items as always. The lone survivor leaves the room to secure the point, and the Select screen keeps the score. To reset the score, delete the ARENA save and make a fresh save.
Head to the official ROM hack page for more info!