Not a Bug
by topsyy_yy
Not a Bug is a Fabric client-side prank mod for 1.21.11 that makes the game look or feel broken in small, random ways, with a panic key to undo everything at once.
What it does
Effects fire at random moments and are never logged, so a player cannot predict or trace them. The set includes 48 pranks that run only on the client, and most of them alter how the world is drawn or how controls respond. Reversed WASD, swapped jump and sneak keys, a Dutch angle that tilts the horizon by 8 to 25 degrees, a drifting aim and a slow spin are among them. Nothing reaches the server, so a player can join any server without the server knowing anything about it.
The mod is published for Fabric only, for the single game version 1.21.11. Fabric API is required. Not a Bug is client-side only, so servers do not need it and every effect is created on the player's own machine and removed when it ends. The MIT License covers the code, but the project is not open source. The panic key stops every effect instantly, and the game returns to how it was before the prank started.
Key features
Random control effects
Reversed movement keys, swapped jump and sneak, and mirrored strafing appear without warning and can last for a while.
Camera and horizon tricks
The camera can tilt, drift or spin slowly, and the horizon can sit at a Dutch angle while the player's aim stays put.
Panic key
One key stops every active effect at once and restores the normal controls and view.
Client-only pranks
All 48 effects run on the client alone, so a join to a server gives no sign of the mod.
Gallery
Compatibility
Latest build for each game version and loader.
Only full game releases are shown. This mod publishes no snapshot builds.
Requirements
Dependencies declared by the latest file for each loader.
Required 1
Use cases
Friendly pranks on a friend
A player can run the mod on a friend's client during a session and let the random effects surprise them without any server setup.
Who it’s for: The mod suits single-player players and friends in a shared game who want unexpected, short-lived disruptions. Server owners have nothing to install, since the effects never reach the server.
How it compares
Spin around is a Fabric client mod for 1.21.1 – 1.21.8 under the MIT License, and it is not open source. O I I A is a Fabric client mod for 1.21.9 – 1.21.11 under the MIT License, and it is open source, so its code can be read freely. Rko Nohurtcam & No Fog is also a Fabric client mod, released for 1.18.2 – 1.20.1 under the MIT License and not open source, and it covers a different set of versions from this one.
| Mod | Loaders | Game versions | Environment | Updated |
|---|---|---|---|---|
| Not a Bug | Fabric | 1.21.11 | Client-side only | 2026-10-03 |
| Spin around | Fabric | 1.21.1 – 1.21.8 | Client-side only | 2025-08-28 |
| O I I A | Fabric | 1.21.9 – 1.21.11 | Client-side only | 2025-12-11 |
| Rko Nohurtcam & No Fog | Fabric | 1.18.2 – 1.20.1 | Client-side only | 2023-08-04 |
Questions
Does Not a Bug need Fabric API?
Does the server need the mod?
How can the effects be stopped?
Is the mod available for other game versions?
In the catalog
Not a Bug is one of 7,555 Cursed mods on ModsFinder, and one of 4,235 Cursed mods for Fabric. 19,862 mods support Minecraft 1.21.11.
Similar mods
What the author says
At a random moment — you never know when, and you can tune how often — this mod does exactly one thing to you: inverts your controls, tilts the horizon, drops lightning next to you, puts a mob behind your back. Then it puts everything back the way it was. Nothing is logged. Nothing is left behind. You just look…
Official listing
- Modrinth page
- modrinth.com/mod/not-a-bug
- Owner
- topsyy_yy
- Published
- 2026-08-15
- Updated on Modrinth
- 2026-10-03
- Facts verified
- 2026-10-15