There was a thing called Adventurecraft for minecraft in 2012, and it was epic. Sadly, it was discontinued and never updated again. But, you could still play it, just no one could figure it out, until I finally did. You could choose from many maps to download for it, my favorite is The Zelda Adventure map. It's really just the first Zelda game, but in minecraft, and with minecraft mobs and stuff, it's really fun. It even has all the Zelda music. You could play for days and days on it. Here are some screenshots. (not very good ones)

Those are just some of the cool things in that map. You can even create your own custom map! So, I bet you guys want to know how to install it? Well, here ya go.
Step 1. Downgrade the minecraft.jar in the bin folder to 1.3.2 (when emeralds were added).
Step 2. Download the "Launcher" for it here:
http://bit/ly/M9FF5w" onclick="window.open(this.href);return false;
Step 3. Click the "AdventureCraft.jar" program (be sure to open that one and not the other ones.
Step 4. Press the "Install via Login" button and enter the minecraft account stuff.
Step 5. It will come up with an error, ignore it. Now click "Install" and it will install.
Step 6. Have fun, and leave a comment if you have any problems.