Adventure Update

The Adventure Update was a major update to focused on fighting, exploration, and adventuring, as well as other aspects. Its content was implemented in Beta 1.8 and 1.0.0. It was announced on June 10, 2011 by Notch and was initially planned to be implemented in Java Edition Beta 1.7. An early version of the Adventure Update was playable by fans at Mojang's booth at PAX Prime 2011, which was held between August 26 and 28. Because of the size of the content, the first part of the update was pushed back to Beta 1.8, which became available on September 14, 2011 and the rest of the update being part of Minecraft 1.0, which was released on November 18, 2011. The pre-releases of Minecraft Beta 1.8 and Beta 1.9 were leaked before their official releases, and Notch approved these leaks on his Twitter.

Changes in Beta 1.8

 * New Mobs.
 * Enderman
 * Silverfish
 * Cave Spiders
 * New Blocks
 * Stone Bricks
 * Stone Brick Slabs
 * Stone Brick Stairs
 * Brick Slabs and Brick Stairs
 * Fence Gates
 * Glass Panes
 * Iron Bars
 * Melons
 * Re-added Creative game mode.
 * New features in the terrain generator.
 * Optionally generated structures
 * Villages
 * Strongholds
 * Mineshafts
 * Ravines
 * New, fractal-based biome code; added and removed some biomes while making all of them more vast than before.
 * Rivers flowing through/in between biomes.
 * Ocean Biomes, that are deeper and much more vast than before.
 * Mountain biome
 * Swamp
 * Snow in Taiga and Tundra biomes do not generate for technical reasons. They return in Minecraft 1.0.
 * New ocean floor; random mix of sand, dirt, and clay.
 * Because of this, clay is much more common.
 * New combat Mechanics.
 * Hold-to-charge bows.
 * Critical hits.
 * Players can parry with a sword by holding, although this was removed in 1.9 due to the addition of shields.
 * Hostile mobs perform attack animations.
 * Mobs killed by players drop tiny flashing Experience Orbs that add to your experience bar.
 * New Food System.
 * There is now a food meter.
 * Food no longer heals directly but indirectly: if the food meter is above 80%, heals about every 5 seconds.
 * All food (except Mushroom Stew) are now stackable.
 * Food takes 1.6 seconds to consume, accompanied with an animation.
 * 5 new food items.
 * Melons.
 * Raw Chicken.
 * Raw Beef.
 * Cooked Chicken.
 * Steak, which has Cooked Porkchop's old texture. Cooked Porkchops' new texture is a tan shade of the same sprite.
 * Eating Raw Chicken or Rotten Flesh has a chance to give the player food poisoning.
 * New seeds for farming: pumpkin seeds and melon seeds that produce Pumpkins and Melons respectively.
 * A new achievement: "Kill a skeleton with an arrow at 50 meters".
 * Added Sprinting
 * Mob changes
 * Passive mobs randomly flee if attacked by the player or other mobs (such as Wolves).
 * Zombies drop Rotten Flesh instead of Feathers.
 * The snout on pigs now protrude from their head.
 * Skeletons now hold full-size bows.
 * Player-to-mob damage decreased by half a heart. Specifically, sword damage used to be ADDED to the half a heart damage the player does with an empty hand and now isn't. Change reverted 2 years later in release 1.6.2.
 * Arrows that hit a mob visually "stick" into the mob rather than just disappear.
 * Skeleton arrows originate from about their eyes to the bow, instead of above the head.
 * Animals no longer despawn, making it possible to capture them.
 * Shears can now collect Tall Grass and the new Vine
 * New improved lighting
 * Day/night cycles no longer require chunk updates and is a smooth transition
 * The lighting on a block is given a tint based on the most prominent source of light
 * Redish from Non-sunlight light sources
 * Blue from Moonlight
 * Total darkness keeps the same black tint
 * Sunlight gives the same white tint
 * Non-sky based light now gives a very subtle 'flicker'.
 * Main Menu/Options changes
 * The Main Menu's background is now an animated scene.
 * The version tag is now displayed on the bottom-left rather than the top-left
 * New sliders for Field of View and Brightness
 * 4 new entries in control list
 * "Attack", "Use Item", and "Pick Block" can now be remapped.
 * Player list in multiplayer, defaults to.
 * The 'Multiplayer join screen' has been improved, mainly with a server list.
 * New texture for Mossy Cobblestone to match Cobblestone's.
 * Improved sunrise and sunset.
 * Clouds change color during sunrise and sunset to match the sky color.
 * Horizon, specifically haze, changes color more vividly during sunset and sunrise.
 * New particle effects.
 * Performing a critical hit on any mob causes 'sparks' to fly.
 * Explosion particles are now shockwaves instead of smoke.
 * Tiny stationary bubble particles can be seen when underwater.
 * Fog is now thicker and darker deep underground, and gives off particles. Due to this, the void appears black.
 * Changes with debug-view
 * Mobs are no longer visibly labeled with their entity ID
 * The world's numeric seed is displayed in a field below player position.
 * Changing fog by hotkey now requires debug-view to be open in addition with pressing.
 * +Clicking the output item in a crafting square crafts all the items at once, and automatically places them in the inventory.
 * The version tag appears in-game again.
 * User-placed leaf blocks no longer decay.
 * Cloud height raised to the top of the map, so clouds can no longer phase through blocks.
 * Cloud movement syncs with the game's time.
 * Rain and snow both render faster
 * Armor bar moved to above hearts, due to food bar.
 * Both Wooden and Stone pressure plates can now be placed on fences.
 * Improved chest model with a 3D lock.
 * Players with the OP position on a server can switch back and forth between survival and creative mode.
 * The game's coding now allows for mods to more easily change the(map) height.
 * Holding the left mouse button with a weapon now swings only once.
 * Holding the right mouse button to place blocks is slightly slower than before.

Bug Fixes:
 * The +Click crash bug from beta 1.8 pre2 is fixed.
 * Fixed Redstone circuits not working after  glitch is now fixed in multiplayer.
 * Destroying boats and minecarts now creates particles.
 * Ghast attack sounds are fixed in multiplayer.
 * The Far Lands had been removed; there is now only ocean.

New bugs:
 * There is a memory leak mainly occurring on Linux 32 bit.
 * The destruction animation for chests is missing.
 * Lighting persists in water even after the light source is removed.
 * Experience orbs when dropped don't drop in a stack like items do, so when a player dies when they have a large number of experience, each orb has to be processed individually. This causes a high amount of lag, especially for multiplayer servers.
 * Double chests placed before beta 1.8 on multiplayer servers all appear to players to be facing the same direction, even when they should be rotated by 90 degrees.
 * The Item Selection screen in the new Creative game mode is missing spruce and birch leaves, tall grass, double slabs, monster spawner, snow cover, and both huge mushroom blocks.
 * NPC villages occasionally spawn over partial water areas and 'float'.

Further revisions

 * Java Edition Beta 1.8.1 converted the support beams in mineshafts from planks to oak fences and fixed two bugs.

Changes in 1.0.0

 * A proper ending to the game in a realm called "The End".
 * New Nether content.
 * Nether bricks (called nether brick at the time)
 * Nether brick stairs
 * Nether brick fence
 * New achievements.
 * Score is stated on death based on total experience orbs held on the player.
 * A new game mode. (Hardcore)
 * New biomes. (Mushroom biome, tundra reintroduced)
 * New items.
 * Eye of ender
 * Blaze powder
 * Blaze rod
 * Glistering melon
 * Glass bottle
 * New texture for some blocks.
 * Block of iron
 * Block of gold
 * Block of diamond
 * Dirt
 * Grass block
 * Stone
 * Planks
 * Gravel
 * Netherrack
 * Glowstone
 * Slab-Bug fixed.
 * New blocks.
 * End stone
 * Brewing stand
 * Cauldron
 * Enchantment table
 * End portal frame
 * New mobs. (Ender dragon (Boss Mob), snow golem,  mooshrooms,  villager mobs, magma cube, blaze)
 * Animal breeding.
 * Potions.
 * Sword rebalance as well as enchantments.
 * Improved Armor system, with slightly more durability.
 * Mob health rebalance. (Sheep, spiders, zombies)
 * New sound effects, including: chest sound, door/gate sound, bow Sound, enderman sound, silverfish sound, explosion sound, egg sound, eating sound, sound when XP orbs are collected, sound of bones cracking after fall damage is taken, sound of a broken tool.
 * Item Repair.
 * New stronghold content (Portal rooms with the end portal frames).
 * Bow now has durability and infinite arrows in creative.
 * Lily Pads that can be placed on water and stood upon.
 * Many blocks are mined faster:
 * Axes mine fences, wooden doors, wooden pressure plates and crafting tables faster.
 * Pickaxes mine obsidian and redstone ore faster.
 * Redstone placed on its own no longer has a "plus" format, instead it has a small clump.
 * Added a World Type option. (Not used until Java Edition 1.1 introduced Superflat)

Further revisions

 * Java Edition 1.0.1 was server-exclusive and fixed some bugs and crashes on servers.

Trailer
Leading up to the release of Beta 1.8, a trailer documenting some of its major features was released on Mojang's official YouTube channel on September 6, 2011. The trailer was made by Hat Films.

Trivia

 * The Adventure Update was the only Java Edition major update to be split into 2 parts until April 14, 2021, in which the Caves & Cliffs update got split into 2 parts.