SkyBlock
The original floating-island survival map. Start with a tree, a chest, lava, and ice. Updated for 1.20+ with modern blocks and mechanics. Works on both Java and Bedrock.
Hand-built worlds for adventure, survival, parkour, and puzzles. Each map lists its edition, the newest Minecraft version it was tested on, and where the download goes. Java maps go into saves. Bedrock maps are usually .mcworld files you double-click to import.
The map file format and install folder are different. A Java map will not open in Bedrock, and vice versa.
Download a .zip, extract it, and drop the folder containing level.dat into %appdata%\.minecraft\saves on Windows. Close the launcher first. The map appears in Singleplayer on next launch [citation:1].
Download a .mcworld file and double-click it — Minecraft imports it automatically. If you get a .zip, rename it to .mcworld or extract it into minecraftWorlds [citation:7].
Two things cause most "the map doesn't work" problems: wrong folder, and wrong game version.
A map built for 1.19 may load in 1.20 but break custom command blocks. If the map page says a specific version, use that version. Do not assume "latest" is fine [citation:1].
On Java, moving files into saves while the launcher is open can cause the game to not detect the map. Close Minecraft completely before extracting [citation:1].
The folder you move into saves must contain level.dat directly inside it. If you see another folder inside, go one level deeper [citation:1].
Fabric and Forge setup from scratch. What folder the JAR goes in, and what to do when the game crashes.
How to read a crash log, identify the failing mod, and remove it without breaking the rest.
Which loader works with which shader pack, and when to pick one over the other.