Number: 404, Unknown
by ratmaker
Unknown is a Forge horror mod that builds a psychological sanity system, in which a hostile entity grows stronger as the player's sanity drops.
What it does
Sanity is tracked as a meter that falls when the player takes damage or triggers certain uncanny events, and that recovers while sleeping or resting in a zone lit by lights. As sanity falls, sounds distort and vision blurs, and the screen can turn black or white. Lower sanity leaves the player less able to stay in control of the situation.
A hostile entity that appears only under that name moves closer over time while the player is unsettled. It can grab the player's feet, make the body fall into the sky, and jumpscare a sleeping player. It also knows the player's name and can address them in chat. Unknown is built for single-player and multiplayer use, and it needs to be installed on both the client and the server.
Unknown is published for Forge only, in one build for 1.20.1, and it is released under All rights reserved, so it is not open source.
Key features
Dynamic sanity meter
Sanity rises during sleep and in lit zones, and it drops after damage or a disturbing encounter.
Distorted perception
Low sanity bends the player's senses with distorted sounds, blurred vision and screen flashes.
Approaching entity
Unknown watches from the darkness and gets closer as the player loses control of the situation.
Frightening interactions
The entity can grab the player's feet, make the body fall into the sky, jumpscare a sleeping player and speak the player's name in chat.
Gallery
Compatibility
Latest build for each game version and loader.
Only full game releases are shown. This mod publishes no snapshot builds.
Use cases
Horror play sessions
Players who want a survival run built on fear and mounting pressure can use the sanity system to set the pace of a night.
Who it’s for: Players who enjoy psychological horror in survival or multiplayer worlds, and server owners who want an entity that reacts to each player's state.
How it compares
Unknown Host is a Forge mod for 1.20.1 with the same client and server environment, under All rights reserved, so it is not open source. R's Sanity System covers Forge and NeoForge across 1.20.1 – 1.21.4 and is also not open source. PSYCHOSYS is Forge-only for 1.20.1 – 1.20.6 and is not open source. ModMcraft is Forge-only for 1.20.1, released under the MIT License, and it is not open source either. The Presence: Unknown is a Forge mod for 1.20.1, released as All rights reserved.
| Mod | Loaders | Game versions | Environment | Updated |
|---|---|---|---|---|
| Number: 404, Unknown | Forge | 1.20.1 | Client and server | 2026-04-04 |
| Unknown Host | Forge | 1.20.1 | Client and server | 2026-10-01 |
| R's Sanity System | Forge and NeoForge | 1.20.1 – 1.21.4 | Client and server | 2025-12-22 |
| PSYCHOSYS | Forge | 1.20.1 – 1.20.6 | Client and server | 2026-08-18 |
| ModMcraft | Forge | 1.20.1 | Client and server | 2024-01-07 |
| The Presence: Unknown | Forge | 1.20.1 | Client and server | 2026-03-17 |
Questions
Which loader does Unknown support?
Does Unknown have to be installed on the server?
Does Unknown need any other mods?
In the catalog
Number: 404, Unknown is one of 7,555 Cursed mods on ModsFinder, and one of 3,426 Cursed mods for Forge. 34,764 mods support Minecraft 1.20.1.
Similar mods
What the author says
Unknown is a psychological horror mod that feeds on the player’s fear and confusion. The entity known only as Unknown watches from the darkness, appearing when your sanity begins to fade. The mod introduces a dynamic sanity system, where your perception of the world changes as your mind deteriorates—sounds distort…
Official listing
- Modrinth page
- modrinth.com/mod/number-404-unknown
- Owner
- ratmaker
- Published
- 2025-11-07
- Updated on Modrinth
- 2026-04-04
- Facts verified
- 2026-10-15