Saturn

What Saturn is

Saturn is a server fork of Paper for Minecraft 1.21.11. You run it as the server itself, in place of the Paper jar. Paper and Bukkit plugins load as they do on Paper.

Saturn is a standalone product. It starts through the Standalone Aegis loader, not as a plugin. See Installation.

What it adds

• Combat profiles. Two profiles, MODERN_1_21 and CUSTOM, each with its own hit cooldown, attack cooldown, sweep, Sweeping Edge, damage tilt and knockback settings. You pick a profile per game mode, world, dimension or for the whole server. See Combat profiles.
• Knockback profiles. Create, edit and assign knockback values in game with /knockback. The next hit uses the new values. Profiles can be saved to disk. See Knockback profiles.
• Entity tracker settings. Set how far an entity must move before the server sends its position, and how often a full position update is forced. Both can be set globally or per world.
• Network flushing. An opt-in mode that merges network flushes for players in game. See Configuration.
• Tab-list ping interval. Set how often the ping shown in the tab list is refreshed.
• Locator bar updates. A player's locator bar updates are sent once per movement packet. On by default and can be turned off.
• Combat history cap. Each entity keeps at most 128 combat entries during continuous combat, so long fights don't keep growing in memory. Death messages are worked out the same as with every entry kept.
• Slime world support. Saturn includes AdvancedSlimePaper's server-side Slime world support. See Slime worlds.
• Error reporting. Optionally send server errors to your own Sentry project. Off until you set a DSN. See Configuration.
• Branded /version. /version shows Saturn's version, the Minecraft and API versions, the build commit and date, and the Java version and operating system. Click the output to copy it.
• Live reload. Edit saturn.yml and run /serverconfig server. No restart is needed.

Every combat setting in saturn.yml starts at the vanilla value, so a fresh Saturn server plays the same as Paper until you change something. The locator bar and combat history settings above are on by default.

Always-on changes

These have no setting:

• Locator bar connections between players are indexed, so the server does less work keeping them up to date.
• Mobs keep a cached list of their AI behaviours instead of walking every behaviour group each tick.
• When a player leaves or another entity is removed, its combat history and last-damage records are cleared so the memory can be freed.
• When no player is hiding another with the Bukkit API, the server skips that visibility check while tracking entities.

What it does not add

• There is no /saturn command. Saturn's commands are /serverconfig and /knockback (alias /kb). See Commands and permissions.
• Saturn has no plugin API or events of its own. Plugins use the Paper API, and the AdvancedSlimePaper API for Slime worlds.
• /swm and database storage for Slime worlds come from AdvancedSlimePaper's separate world plugin, which is not part of Saturn.

Requirements

When Saturn starts

Saturn reads saturn.yml early in startup, before worlds load, to set up error reporting. It creates the file then if it is missing. The rest of Saturn, including combat, knockback and the /serverconfig and /knockback commands, starts on the server's first tick, after worlds and plugins have loaded.