Death Regression

Death Regression rewinds your world when you die.

Instead of respawning, the entire world goes back to your last checkpoint: terrain, blocks, chests, mobs — everything returns to exactly how it was when the checkpoint was made. You reappear at the checkpoint position with full health.

This is a full save rollback, not a respawn tweak.
Singleplayer only.

!! WARNING !!

This mod REPLACES your world save folder during a rollback.
Anything you built or changed after the checkpoint WILL BE LOST.
Back up your world before using it for the first time.

!! SINGLEPLAYER ONLY !!

This mod is designed for singleplayer.

Multiplayer (LAN worlds and dedicated servers) is not supported.
The rollback relies on the game stopping its internal server, which only
happens automatically in singleplayer.

===== HOW SAVING WORKS =====

When are checkpoints created?

Three automatic triggers:

- Sleeping (SLEEP)
  Triggers when you sleep in a bed.

- Game days (DAYS)
  Every N in-game days, triggered by chance.
  Default: every 10 in-game days, 50% chance.
  In other words, not every 10 days creates a checkpoint — it is a coin flip.

- First join (INITIAL)
  The first time you enter a world that has no checkpoint yet, one is created immediately, so you are never without something to roll back to.

Choose which triggers are active with:

  /regression config saveMode SLEEP|DAYS|MIXED

  SLEEP   sleeping only
  DAYS    game days only
  MIXED   both (default)

Two manual methods also exist:

  /regression save                                 create a checkpoint now
  /regression config manualSaveItem <item ID>      right-click while holding this item

How often can it save? (cooldown)

Automatic checkpoints have a minimum interval so they do not pile up.

  Default: 100 minutes (real time).

While the cooldown is running, sleeping or reaching the day interval does nothing; you get a "cooldown, X remaining" message instead.

Change it with:

  /regression config saveCooldownMinutes 1~1440

How many checkpoints are kept?

Default: 3 per world.

  saves/regression_backups/<world>/backup_0
  saves/regression_backups/<world>/backup_1
  saves/regression_backups/<world>/backup_2

Once all slots are used, the next checkpoint overwrites the oldest one, starting from backup_0 and cycling. Think of it as a ring buffer that always holds the most recent N checkpoints.

Change it with:

  /regression config maxBackups 1~20

Important: a rollback uses the checkpoint with the newest timestamp, not the highest slot number.

Other limits

- Full health required (requireFullHealth, default on)
  The player must be at full health for an automatic checkpoint. Sleeping while damaged will not create one.

- Dimension blacklist (blacklistedDimensions, default empty)
  Dimensions listed here will not create checkpoints, and dying there will not trigger a rollback. Adding minecraft:the_nether, for example, makes the Nether unaffected.

- World identity
  Each checkpoint records which world it belongs to. If you delete a world and create a new one with the same name, the old checkpoints are cleaned up automatically instead of being used by mistake.

What is stored in a checkpoint?

A full copy of the world folder:

  region/*.mca      terrain and blocks
  entities/*.mca    mobs and dropped items
  playerdata/       player data
  level.dat         world metadata
  DIM-1/ DIM1/      Nether and End

So a rollback rewinds the entire world, not just your location.

What happens when a checkpoint is created

  1. The server saves the world completely
  2. It waits for chunk writes to settle (avoids copying half-written files)
  3. The whole world folder is copied to the backup directory
  4. Chunk files are verified and re-copied if incomplete
  5. Checkpoints beyond the limit are deleted

What happens on a rollback

  1. You die and the rollback starts
  2. The server stops and disconnects you
  3. The world folder is replaced with the newest checkpoint
  4. Player data is merged according to your settings
  5. The client reconnects automatically

No manual action is needed, but you will be kicked out and back in within a few seconds.

===== PLAYER DATA (OFF BY DEFAULT) =====

By default the mod only rolls back the world and keeps no player data:

  you die -> the world returns to the checkpoint -> you return with it
  your inventory becomes whatever it was at the checkpoint
  anything you picked up, crafted or bought after the checkpoint is gone

This is identical to loading a save manually, and it is the default behaviour.

Turning it on

  /regression config keepPlayerData true

Now the behaviour changes:

  the world still rolls back to the checkpoint
  but your inventory and player data keep the state from the moment you died
  items you obtained after the checkpoint survive the rollback

Note the difference: it keeps the state at your death, not the state at the checkpoint.
Five diamonds in your inventory when you died means five diamonds after the rollback.
An empty inventory when you died means an empty inventory after the rollback.

Choosing which categories to keep

With the master switch on, each category can be toggled separately (all on by default):

  inventory
  armor (helmet, chestplate, leggings, boots + offhand)
  ender chest
  XP (level, progress, total, enchanting seed)
  hunger
  potion effects (including negative ones)
  absorption (golden apple hearts)
  air (remaining breath underwater)
  scoreboard score
  respawn point (bed / anchor)
  mod data (accessories, skill trees, etc.)

Examples:

  ender chest only  -> keep only keepEnderChest
  inventory only    -> keep only keepInventory
  accessories only  -> keep only keepModData
  everything        -> just enable the master switch

Always taken from the checkpoint (not configurable)

  position
  health
  fire ticks
  fall distance
  death state

In-game menu

  /regression config playerdata

Opens a clickable list where each entry has an [ON] / [OFF] button.
Click to toggle; no commands required.

===== COMMANDS =====

Viewing

  /regression config                     show every setting for this world
  /regression config playerdata          clickable menu
  /regression config <option>            show one option, e.g. keepInventory

Changing

  /regression config <option> true|false
    e.g. /regression config keepEnderChest true

Player data options

  keepPlayerData     master switch
  keepInventory      inventory (36 slots)
  keepArmor          armor + offhand
  keepEnderChest     ender chest
  keepXp             experience
  keepHunger         hunger
  keepEffects        potion effects
  keepAbsorption     absorption
  keepAir            air
  keepScore          scoreboard score
  keepSpawnPoint     respawn point
  keepModData        mod data

Saving

  /regression save                                    create a checkpoint now
  /regression config backups                          list existing checkpoints
  /regression config saveMode SLEEP|DAYS|MIXED        save triggers
  /regression config saveCooldownMinutes 1~1440       cooldown in minutes
  /regression config daysInterval 1~365               day interval
  /regression config daysProbability 0.0~1.0          chance for day saves
  /regression config maxBackups 1~20                  checkpoints to keep
  /regression config manualSaveItem <item ID|none>    item that creates a checkpoint
  /regression config blacklistedDimensions add <dim>      add to blacklist
  /regression config blacklistedDimensions remove <dim>   remove from blacklist
  /regression config blacklistedDimensions clear          clear the blacklist

Other

  /regression stats                                   statistics
  /regression reload                                  reload the config
  /regression config deathRegression true|false       master switch for the mod
  /regression config requireFullHealth true|false     require full health to save
  /regression config easterEgg true|false             chat easter egg

===== CONFIGURATION =====

Every setting is stored per world:

  saves/<world>/serverconfig/regressionmod-server.toml

Changing something in one world does not affect another. All options can be changed in-game and take effect immediately.

===== DEFAULTS =====

  death regression master switch   ON
  keep player data                 OFF
  inventory / armor / ender chest / XP   ON
  hunger / effects / absorption / air / score   ON
  respawn point                    OFF
  mod data                         OFF
  save mode                        MIXED
  save cooldown                    100 minutes
  day interval / chance            10 in-game days / 50%
  require full health              yes
  max checkpoints                  3
  chat easter egg                  ON

Note: the category switches default to ON, but the master switch is OFF, so out of the box nothing is kept — identical to loading a save.

===== PERMISSIONS =====

All /regression commands require permission level 2 (operator).
In singleplayer, enable cheats when creating the world.

===== KNOWN ISSUES =====

- When a new world is created, the first backup may have a few region files that fail the integrity check. Affected areas may appear ungenerated after a rollback. Player data is not affected.
- Singleplayer only. Multiplayer is not supported.
- Requires Minecraft 1.20.1 and Forge.

===== LICENSE =====

MIT