Simulatica
by ryan100c
Simulatica lets a player run a Litematica projection as a live, simulated build, so the blocks and block entities in it react to one another.
What it does
Once a projection is loaded in Litematica, the simulation can be started on it and stopped again from the same workflow. While a simulation runs, the blocks and block entities of the projection behave as they would in a world, and blocks placed next to each other within the projection influence one another. Projections that are simulated cannot overlap, which keeps each run self-contained.
The client creates a local integrated server as soon as at least one simulation has started, and it initializes an empty dimension and loads the target projection into it before simulating. The mod adds client-side lag while simulations are active, so large projections can slow the game. Simulatica is open source under the MIT License and is published for Fabric 1.21.11, with 2.0.0 as the latest file in the beta channel, dated 2026-08-24.
Key features
Simulated block entities
Block entities in a Litematica projection are simulated, so their behavior can be checked before a build is placed in the world.
Start and stop control
A simulation can be started on a projection and stopped again, returning the projection to its unsimulated state.
Non-overlapping simulations
Simulated projections cannot overlap, so one run does not interfere with another.
Neighbor interaction
Nearby projections affect each other during a simulation, which matters when several builds sit close together.
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
Who it’s for: Players who use Litematica to plan builds and want to see how the blocks and block entities in those projections behave before placing them in a world.
How it compares
Litematica Backup is a Fabric client-side mod for 1.21 – 26.3 under the MIT License, but it is not open source and does not simulate projections. QuickCraft is also client-side for Fabric 1.21 – 26.3 under the MIT License, and it is open source. SchematicPreview is client-side for Fabric 1.21 – 26.3 under All rights reserved and is not open source. Better Material Lists is client-side for Fabric 1.21.10 – 26.3 under the CC0 1.0 Universal license and is open source.
| Mod | Loaders | Game versions | Environment | Updated |
|---|---|---|---|---|
| Simulatica | Fabric | 1.21.11 | Client-side only | 2026-08-24 |
| Litematica Backup | Fabric | 1.21 – 26.3 | Client-side only | 2026-10-03 |
| QuickCraft | Fabric | 1.21 – 26.3 | Client-side only | 2026-10-04 |
| SchematicPreview | Fabric | 1.21 – 26.3 | Client-side only | 2026-09-23 |
| Better Material Lists | Fabric | 1.21.10 – 26.3 | Client-side only | 2026-10-07 |
Questions
Does Simulatica need Litematica?
Does Simulatica have to be installed on a server?
Why does the game lag while a simulation runs?
Which Minecraft version does Simulatica support?
In the catalog
Simulatica 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.
More from ryan100c
Similar mods
What the author says
Once at least one simulation has started, a local integrated server is created on the client thread. It initializes a completely empty dimension and loads the target projection to be simulated into it.
Official listing
- Modrinth page
- modrinth.com/mod/simulatica
- Owner
- ryan100c
- Published
- 2026-08-24
- Updated on Modrinth
- 2026-08-24
- Facts verified
- 2026-10-15