the game
MU Online
MU Online is a fantasy MMORPG created by Webzen in South Korea in the early 2000s. Besides the official server, the game lives on hundreds of private servers, each running a different version, from classic 97d to the latest seasons. This page explains what changes between them and where to find each topic in the codex.
How the game works
You create a character of one class, level up hunting monsters on ever harder maps and split points between Strength, Agility, Vitality, Energy (and Command, for the Dark Lord). Gear has upgrade levels (the maximum changes from version to version), extra options and sets; jewels (Bless, Soul, Life, Chaos) upgrade it and double as currency between players.
Scheduled events such as Blood Castle, Devil Square and Chaos Castle give experience and items. Guilds fight for Castle Siege. Many private servers add resets: at a set level, your character goes back to level 1 and gains extra points.
Versions and seasons
MU got updates called versions (97d, 99b, 1.0…) and later seasons (Season 1 to today's). Each added classes, maps, items and systems. Private servers pick a version and usually customize it. The table shows the size of each version in the server bases we document:
| Version | Items | Armor pieces | Monsters | Maps | Skills |
|---|---|---|---|---|---|
| 97d | — | — | 103 | 6 | — |
| 0.99B | 89 | — | 156 | 9 | — |
| 1.0 | — | — | 188 | 10 | — |
| Season 2 | 255 | 190 | 180 | 13 | 77 |
| Season 3 | 274 | 190 | 198 | 16 | 79 |
| Season 4 | 384 | 248 | 206 | 59 | 344 |
| Season 5 | 408 | 287 | 269 | 20 | 145 |
| Season 6 | 562 | 327 | 295 | 32 | 339 |
| Season 7 | — | — | — | 22 | — |
| Season 8 (Ep. 3) | 707 | 351 | 351 | 33 | 323 |
| Season 9 | 775 | 351 | 404 | 34 | 323 |
| Season 10 | 936 | 414 | 393 | 35 | 371 |
| Season 11 | — | — | — | 33 | — |
| Season 12 | 1144 | 517 | 549 | 49 | 442 |
| Season 13 | 1067 | 594 | 470 | 42 | 545 |
| Season 14 | 1427 | 672 | 433 | 61 | 493 |
| Season 15 | 1497 | 819 | 458 | 65 | 548 |
| Season 16.2 | 1560 | 916 | 475 | 67 | 602 |
| Season 17 | 1632 | 1114 | 424 | 70 | 670 |
| Season 18.2 | 1996 | 1469 | 528 | 74 | 705 |
| Season 19.2-3 | 2242 | 1497 | 669 | 69 | 826 |
| Season 20 | 2481 | 1998 | 581 | 80 | 786 |
Counts of what was read from each base. “—” means that base's table was not read (undocumented columns, or names stored in Korean in the file, as in the Season 7 and Season 11 bases), not that the content did not exist.
Where to start in the codex
- Classes: starting stats, gear and skills for each.
- Items, sets and wings: stats by version, requirements and who can use them.
- Maps and monsters: where each monster spawns and level bands for leveling.
- Guides: jewels, reset, Chaos Machine, quests and more.
- Servers: a directory of what each server declares.
- Troubleshooting: black screen, DLLs, lag, connection.
Official and private
Official MU Online is run by Webzen. Private servers are independent projects with their own rules, experience rates and items. This codex's data comes from emulator files named on each page, so always check the rules of the server you play on.
FAQ
Is MU Online still around?
Yes. There is Webzen's official server and many active private servers across several versions.
Which MU version is best to start with?
It depends on what you want: old versions (97d, 99b) are simpler; seasons such as 4 and 6 have more classes and systems. See each season's page in the codex.
Is MU Online free?
It is free to play, both on the official server and on most private servers, which fund themselves with optional paid items and perks.
If you are looking for somewhere to play MU now, MU Éter is a Season 4 server with its own systems, run by the team behind this site.
Discover MU ÉterMMO GRID is maintained by the MU Éter team.Sources
- Documented server bases: 97d, 0.99B, 1.0, Season 2, 3, 4, 5, 6 and 20 (named on each page)
Demand snapshot: SNAP-20261001-1040 · Data extracted on 2026-10-01