Gameplay Data Packs

Sleep and the night

Two of these packs work on the same vanilla rule. players_sleeping_percentage sets how many of the players in the Overworld must be in bed before the night is skipped. The default is 100, so everyone; at 0 a single sleeper is enough, and above 100 the night can't be skipped at all. The rule arrived in Java 1.17 as playersSleepingPercentage and got its new name in 1.21.11, so a pack whose functions still use the old name stops working on newer versions.

A bed works once the sky light has dropped to 11: from tick 12,523 to 23,477 in clear weather, from 12,002 in rain, and at any hour during a thunderstorm. The night skips after 101 ticks in bed, about five seconds. Phantoms go by each player's own Time Since Last Rest, which only lying in a bed or dying resets, so a player who never sleeps still meets them after three in-game days while the others skip every night. Pick either Multiplayer Sleep or Custom Sleep Percentage, not both.

Deaths, heads and graves

In vanilla your items fall where you die and disappear after 5 minutes in a loaded chunk. Of your experience only 7 points per level drop as orbs, never more than 100, and the rest is lost. keep_inventory keeps both, which is also why Graves has nothing to store while that rule is on.

A player head can't be obtained in vanilla survival at all. It only comes from the Creative inventory, pick block or /give, and that is the gap Player Head Drops and Wandering Trades (Hermit Edition) fill.

The wandering trader

Every world counts down 24,000 ticks, one in-game day. Each time the counter runs out there is a 2.5% chance of a trader, rising to 5% and then 7.5% after failed tries. It appears near a random player, or near a bell if one is within 48 blocks of that player, with two trader llamas on leads. In Java it leaves after 48,000 ticks, 40 minutes, while one from a spawn egg or /summon never despawns. Setting spawn_wandering_traders to false stops natural spawns.

Hermit Edition swaps its trade list for mini blocks and heads. The vanilla trades changed as well in Java 1.21.5, when the wandering trader part of the trade rebalance left the experiment.

Villager trades and the rebalance experiment

Trade Rebalance is Mojang's own experiment, and in Java 26.2 it still is one, next to Minecart Improvements and Redstone Experiments. Turn it on in the Experiments screen while creating the world, or on a server with initial-enabled-packs=vanilla,trade_rebalance in server.properties before the world is generated.

Librarians change most. They stop offering every enchanted book: which books one sells depends on the biome the villager comes from, special books with a fixed level only come from master librarians, and enchantments unique to the crossbow, fishing rod, trident, mace and spear can't be bought at all. The experiment also changes chest loot, with more Mending books in ancient cities, Unbreaking in desert and jungle pyramids, Efficiency in mineshafts and Quick Charge at pillager outposts. A pack that rewrites villager trades, such as Custom Villager Trades, clashes with it, so run one or the other.

Portals, ores and enchanting

Custom Nether Portals

A vanilla portal is an upright rectangle of obsidian, at least 4 by 5 blocks and at most 23 by 23 with the frame counted. The four corners can be left out. Other shapes don't light, and neither does a frame lying flat like an End portal.

XP Boost Ores

Vanilla gives 0 to 1 experience for nether gold ore, 0 to 2 for coal, 1 to 5 for redstone, 2 to 5 for lapis and nether quartz, and 3 to 7 for diamond and emerald. Iron, copper and gold ore drop raw metal and give experience only when you smelt it, ancient debris gives none when mined, and an ore broken with Silk Touch drops no experience.

Better Enchanting

The vanilla table reaches its top offer, level 30, with 15 bookshelves around it and one block of air in between. You need the level shown but only pay 1, 2 or 3 levels and the same number of lapis, and what you get is random: a level 30 offer can still give nothing more than Efficiency III.

Bundles no longer need a pack

Bundle (Vanilla Experiment) belongs to the versions before 1.21.2, when a bundle was still an experiment crafted from two string and six rabbit hide. Java 1.21.2 made bundles part of the normal game and removed the experiment. Now a bundle takes one string and one leather, comes in 16 dyed colors and holds one stack's worth: a stick fills 1 of its 64 spaces, an ender pearl 4 and a sword all of them.