SubTick

Carpet is required, and SubTick builds on its rules and commands rather than replacing them. The extension lets a server operator freeze or unfreeze the game just before a chosen tick phase, step a given number of ticks that end right before that phase, or step through phases forward within the current tick or the next one. Tick stepping works with tick step 0 to resolve a later phase inside the same tick.

The queueStep command advances through a count of queued elements, either inside the current tick or on the next tick, and an unlimited range can be set with -1. Fluid ticks, block ticks, block events, entities and block entities can be stepped individually, and block events can be stepped through whole depths or by block tick priorities. A client-side HUD shows highlights for the elements being processed.

Only the server needs SubTick for its stepping commands to take effect, while a player may add it and joining clients can leave it out. The mod is open source under the GNU Lesser General Public License v3.0 only. It is published for Fabric only, across 8 release versions 1.17 – 1.20.1, with 2.1.1 for 1.20.1 as the latest file. Source code and an issue tracker are publicly linked.