- The addition of the Nether: a "Hell" world that can be used for quick travel, where you "portal in" walk ten meters and then "portal out" and you are 80 meters away. Movement in The Nether in relation to the normal world is 1:8, meaning that for every block (meter) traveled in The Nether, 8 blocks are traveled in the normal world.
- 2 new mobs (Ghasts and Zombie Pigmen)
- Deeper areas are more dangerous due to increased chances of Lava pits, and mobs are more likely to spawn lower down.
- This was removed by Notch in a later update.
- Fishing using fishing rods
- 6 new block types (Glowstone, Netherrack, Soul Sand, Pumpkins, Jack-O-Lanterns, Portals)
- Multiplayer bug-fixes
- Craftable Jack-O-Lanterns, and the ability to wear pumpkins.
- Craftable clock
- New sounds and music
- Dawn and dusk now have reddish colors just like real sunsets and sunrises.
- Every Halloween, every mob wears a jack-o-lantern on their head.
Torches were planned to become temporary light sources with the new permanent light source being lanterns, but the update didn't make it in time.
- The update was announced on October 4, 2010, as seen at Notch's blog.
- On October 8, 2010, a new type of block was announced. And on October 11 Notch wrote the following on his twitter: "I just made the most unfair mob ever even more unfair. You will hate the Ghast."
- On October 10, 2010, Notch revealed the following screenshot on his blog:
- On October 19, 2010, Notch added the following on his blog: "There are six new block types (five of them have unique abilities), one new monster, a new dimension, and a couple of bug fixes."
- On October 22, 2010, this article appeared on the PC Gamer website, giving more details about the new update. The article states that ghasts are flying cuboid jellyfish that destroy blocks and shoot fireballs at players, and that portals to get to and from the Nether dimension will be made from Obsidian.
- On October 25, 2010, Notch tweeted: "Anyway! I'm working on the second new mob today, and it's far less dangerous than the Ghast. Right now they're kind of pointless, actually!"
- On October 29, 2010, Indie Games and PC Gamer published new articles about the Halloween update, with reviews, videos and screenshots. Both sites have uploaded a second video, PC Gamer's is called Slipgate Adventures, and Indie Games' second video can be found here.