Conveyor Works

A small factory puzzle. Raw items leave the source; a processor finishes them; the sink counts finished products. Build the line between them around the rocks — and with two inputs, merge them.

Lay belts from the source through a processor to the sink and deliver 10 products in 120 ticks.

FreeOn this device

Level

Grey dots are raw items, amber squares finished products. Items move together each tick; a tile that is full at the start of a tick can't take another. Mergers take turns between inputs; splitters alternate outputs. Solved on this device: 0 of 12.

Tick 0 of 120 · delivered 0 of 10 · stopped.

Controls

Choose Belt, Splitter, Merger or Processor and a direction (Rotate or R), then tap a tile or press Enter on it to place the piece. Erase or Delete removes it.
Run plays the line, Pause stops it, Step advances one tick, Reset run empties the line and keeps your design.
Clear design removes everything you placed on this level. Sources, sinks and rocks are fixed.

The rules

Each tile holds one item. Every tick all moves are decided first, then made together; a tile that is full at the start of a tick cannot take another.
When two items want the same tile, a merger takes turns between its inputs; otherwise the lower-numbered tile goes first. Splitters alternate between their two outputs.
A processor takes one raw item and, 3 ticks later, holds a finished product until it can pass it on. Sources release a raw item every 2 ticks. Only finished products count at the sink.

Scoring, saving and limits

Deliver 10 products within 120 ticks. Items are never lost or overwritten, and a line that loops forever simply stops at the tick limit.

Your placed tiles for the current level and the levels you have solved are kept on this device only. Download a backup to move them.

Twelve layouts, each built around a known working line that is tested to deliver the target. There are no random jams.

Questions

Why did an item stop when the tile ahead was emptying?: A tile full at the start of a tick can't receive that tick, even if its item leaves — so a packed belt moves like a queue.
Do raw items count at the sink?: No. They are recorded as unprocessed, which usually means the line bypasses the processor.
What is a merger for?: Joining a second input onto your line fairly: when both sides are waiting, it alternates between them.