Re:Loop

Any problem or bug please comment so i can fix it.

Re:Loop is an experimental Forge mod for Minecraft 1.20.1 that adds a Return by Death inspired timeline rollback system. Instead of working like a normal respawn mod, Re:Loop attempts to restore the world, the player, and nearby important events back to a previous checkpoint after death.

The mod is designed around the idea of surviving through repeated loops while the world reacts to dangerous situations, exploration progress, boss encounters, multiplayer proximity, inventory changes, and major actions performed after a checkpoint.

Re:Loop is currently in Alpha, so some systems may still be incomplete, unstable, or incompatible with certain heavily modded setups.

Main Features

Return by Death System

Re:Loop assigns a Return by Death holder and uses that player as the main trigger for timeline restoration. When the holder receives lethal damage or dies, the mod attempts to cancel the normal death flow and restore the current timeline back to the latest valid checkpoint.

The system can restore:

Player position
Dimension
Rotation
Health
Absorption
Hunger
Saturation
Exhaustion
Air supply
Fire ticks
Fall distance
Frozen ticks
Experience level
Total experience
Experience progress
Inventory
Selected hotbar slot
Ender chest
Active potion effects
Forge player data
Forge capabilities, including support for portable equipment-style data such as Curios-like slots, accessories, artifacts, rings, belts, necklaces, relics, and similar modded equipment systems

Re:Loop also includes verification passes after a return to make sure the player’s restored inventory, ender chest, portable equipment capabilities, and survival stats stay synchronized after the rollback.

Adaptive Checkpoints

Re:Loop does not simply save every few seconds. It uses an adaptive checkpoint director that tries to decide when a checkpoint makes sense based on the player’s situation.

The checkpoint system can recognize many different contexts, including:

Stable safe areas
Player homes
Sleeping in a bed
Returning home after surviving danger
Safe idle or pause-like moments
Logout-safe situations
Movement-based exploration progress
Escaping from danger
Desperate escape situations
Safe areas near danger
Safe pockets inside dangerous areas
Wounded-but-stable danger moments
Dangerous standoffs
Cave entries
Dungeon entries
Structure entries
Structure unlock moments
Structure threshold moments
Cleared structures
Cleared dungeons
Temporary camps
Temporary homes inside dangerous areas
Secured paths
Loot secured after exploration
Valuable loot secured
Base defense moments
Survived raid or event-like situations
Boss hunt progress
Boss boundary entries
Boss entries
Boss resolved situations
Boss exit safety
Teleport transitions
Safe teleport arrivals
Dimension entries
Secured dimension arrivals
Pre-dimension entry moments
Home teleport arrivals
Prepared departures before important actions
Commitment actions before risky events

The system also blocks bad checkpoints when the player or party is in an unsafe state, such as:

Being dead or dying
Being on fire or in lava
Falling
Recently taking damage
Being inside an unsafe open container
Being in a vehicle or passenger relationship
Being too new to capture safely
Being in an unsafe transition
Having unresolved rollback debt from a previous return
Having nearby players in unsafe states when they are part of the checkpoint context

This is meant to avoid saving the player into impossible or unfair situations.

Multiplayer Timeline Restoration

Re:Loop supports multiplayer timeline logic. When a return happens, the mod can restore connected players that are part of the active timeline context, not only the player who died.

It tracks player snapshots and can restore multiple players during the same return operation. It also considers proximity, shared progress, relevant player impact, and party safety before accepting a new checkpoint.

The mod includes shared fate-style checkpoint behavior for certain home-return situations, where other players may affect whether a checkpoint is accepted immediately or delayed until the group is safe.

World Time and Weather Rollback

Re:Loop stores world timeline state at checkpoints and attempts to restore:

World day time
Weather state
Rain state
Thunder state
Rain timer
Thunder timer
Clear weather timer

This helps the return feel like a real timeline rollback instead of only moving the player.

Block Rollback System

Re:Loop tracks block changes after checkpoints and attempts to restore them during a return.

The block rollback system can track and process:

Broken blocks
Placed blocks
Replaced blocks
Block state changes
Block entity NBT changes
Crop growth
Farmland trampling
Tool-based block modifications
Fluid block placement
Neighbor block updates
Nether portal area changes
Explosion-affected blocks
Fire and combustion-related changes
Gravity-sensitive blocks
Waterlogged states
Redstone-like states
Multipart-style blocks
Support-dependent blocks
Connectivity-sensitive blocks
Blocks with inventories or block entities

The rollback classifier separates simple blocks from more complex cases. It uses safety flags instead of blindly restoring everything the same way. This helps reduce corruption risk with fluids, block entities, modded blocks, inventories, gravity blocks, connected blocks, and complex block states.

Block Entity and Container Restoration

Re:Loop can track block entity containers and restore their stored NBT during a return.

This includes container-like block entities such as chests and other inventory-based blocks, with special handling to avoid capturing already-modified states as the new truth.

The mod also tracks container interactions, deposits, withdrawals, slot changes, open containers, and close scans so item movement during a loop can be restored more accurately.

Item, Drop, and Pickup Handling

Re:Loop includes dedicated item return logic instead of treating all dropped items as generic entities.

It tracks:

Items tossed by players after a checkpoint
Items picked up after a checkpoint
New item entities created after a checkpoint
Block drops created after block breaks
Item entities that should be cleaned during return
Items that should be restored if they were picked up after the checkpoint
Deferred item return debt when chunks are not loaded

The goal is to prevent common rollback bugs such as duplicated drops, deleted player-thrown items, missing picked items, or cleanup systems deleting items that were created during the return itself.

Experience Orb Handling

Re:Loop tracks experience orbs created after a checkpoint and attempts to clean or restore them correctly during a return.

It includes deferred return debt for XP orbs when chunks are not loaded, and it can request temporary chunk tickets so delayed XP cleanup can finish instead of silently being lost.

Entity Rollback System

Re:Loop tracks several kinds of entities separately:

Temporary entities
Projectiles
Area effect clouds
Lightning
Arrows
Tridents
Snowballs
Eggs
Ender pearls
Experience bottles
Potions
Fireballs
Wither skulls
Shulker bullets
Fishing bobbers
Decoration entities
Armor stands
Item frames
Paintings
Display-like entities
Living entities
Modded mobs
Boss-like entities
Runtime boss effects
Falling blocks
Primed TNT
Transient explosives

Living entities can be captured using snapshot transactions. Re:Loop attempts full NBT restoration when safe, and falls back to safer adapted restoration when full NBT could be risky.

For living entities, Re:Loop can restore or reapply:

Entity type
Position
Rotation
Motion
Gravity state
Ground state
Health
Absorption
Air supply
Fire ticks
Frozen ticks
Fall distance
Main hand item
Offhand item
Armor
Active effects
Basic AI combat cleanup, such as clearing targets and aggression after restoration

If an entity appears structurally complex, such as multipart entities, mounted entities, entities with passengers, owned or tamed entities, boss-phase entities, brain or capability-heavy entities, or modded entities with risky internal data, Re:Loop avoids forcing unsafe full NBT restoration and keeps restoration debt instead of pretending the rollback is complete.

Boss and Dangerous Event Handling

Re:Loop includes boss-aware rollback logic. It can detect possible boss activations through block interactions, entity interactions, spawner-like systems, portals, boss-like entities, and high-health or boss-named mobs.

The system tries to distinguish between:

Main boss entities
Runtime boss attacks
Projectiles
Hazards
Persistent boss mechanics
Visual or interaction entities
Static decoration entities
Activator-like entities
Boss arena mechanics

This helps avoid deleting important modded boss controllers or breaking boss arenas while still cleaning temporary attacks, projectiles, hazards, and post-checkpoint entities that should not survive a return.

Explosions, TNT, Falling Blocks, and Fire

Re:Loop has dedicated handling for dangerous physics-like events.

It can track and process:

Explosion-affected blocks
Post-explosion drop cleanup zones
Primed TNT created after checkpoints
Checkpoint TNT and explosive entities
Falling block entities
Checkpoint falling block restoration
Fire spread and combustion-related blocks
Post-checkpoint fire cleanup

This is designed to make returns more consistent after explosions, falling blocks, TNT chain reactions, and fire-based damage.

Chunk-Aware Deferred Rollback

Re:Loop does not simply give up when a rollback target is in an unloaded chunk.

The mod tracks deferred rollback debt for:

Unloaded block rollback records
Block entity container restoration
Item restoration
XP orb cleanup
Entity restoration
Living entity verification
Block rollback verification
Chunk-based return work

It can request temporary return chunk tickets so delayed rollback work can continue later when the needed area becomes available.

Return Verification and Debt System

Re:Loop tracks unfinished return work as real rollback debt.

This includes debt for:

Items
Item chunk work
Container slot restoration
Block entity containers
Block drops
Block rollback queues
Unloaded block rollback
Return chunk tickets
XP
Falling blocks
Explosives
Fire
Entities
Block rollback verification
Block state checks

If critical rollback debt is still pending, Re:Loop can block new checkpoints so the mod does not save an incomplete or corrupted post-return state as the new timeline.

Client Effects

Re:Loop includes client-side feedback for the return experience.

Current client effects include:

Return by Death sound
Short return fog effect
Vanilla-style return effects
Death pressure visuals
Monochrome exposure system
Monochrome awakening progression
Shader-based monochrome effect buckets
Network packets for return fog, death pressure, monochrome state, and forced respawn handling

The visual systems are tied to loop progression, memory, death pressure, and exposure to returns.

Loop Progression

Re:Loop tracks player-specific loop data, including:

Return holder status
Awakened return holder status
Return affinity
Loop memory
Witch scent
Last return time
Death pressure
Death pressure streak
Exposure count
Monochrome exposure
Monochrome lock state
Loop count
Checkpoint impact
Advancement impact
Boss kill impact
Item, block, and entity impact after checkpoint

Death pressure can increase depending on the type of death, repeated deaths, valuable losses, boss-like progress, challenge advancements, and major post-checkpoint progress. It can also decay over time after surviving.

Impact Tracking

Re:Loop tracks important actions after a checkpoint to understand how meaningful the current loop has become.

Tracked impact includes:

Block breaking
Block placing
Item pickups
Item tosses
Entity kills
Boss kills
Advancements
Advanced advancements
Challenge-like advancements
Valuable item loss
Inventory value changes
Ender chest value changes

This data is used for death pressure, checkpoint decisions, and loop progression.

Safety-Oriented Mod Compatibility

Re:Loop is built with modded survival in mind. It does not try to solve compatibility by simply ignoring all modded content.

Instead, it uses classification, staged restoration, deferred debt, verification, and safer fallback behavior for difficult cases.

For risky modded content, Re:Loop may:

Restore full state when safe
Restore partial physical or vital state when full state is unsafe
Use adapted restoration for equipment and effects
Keep debt for later verification
Soft-protect entities after repeated rollback failures
Avoid forcing unsafe NBT on complex mechanics
Avoid saving a new checkpoint while critical restoration work is unfinished

Current Alpha Status

Re:Loop is still experimental.

This version may still contain bugs, crashes, incomplete rollback behavior, or compatibility issues, especially in large modpacks or with complex modded systems.

Known areas that may still need testing and improvement include:

Complex modded entities
Boss mechanics
Multipart mobs
Entity controllers
Modded inventories
Backpack-like systems
Curios-like systems
Portals
Dimensions
Explosions
Fluids
Block entities
Drops
XP orbs
Multiplayer returns
Large modpacks
Heavy survival servers

Please treat this version as an early Alpha build and report issues with logs, reproduction steps, Minecraft version, Forge version, modpack information, and a clear explanation of what happened before and after the return.

Recommended Use

Re:Loop is recommended for players who want an experimental, high-risk survival mechanic inspired by timeline loops and Return by Death-style consequences.

It is best used in testing worlds or modpacks where players are comfortable with Alpha behavior and willing to report issues.

This mod is not yet recommended for important long-term worlds without backups.