Sandustry Demolisher and Red Blocks

The Demolisher is the tool behind the X key. Official wiki language: it removes player-placed blocks except Pipes (pipes use Pipe Remover). You hold X and drag a box, the same marquee idea as Keyboard Shortcuts. Until Early Access week, that was enough. Then indestructible red blocks started showing up in open terrain and on puzzle doors, and a wipe that should have cleared a corridor left a wall of red. Update 0.5.4 is the workaround, not the final engine fix.

Default use

1. Select the Demolisher (or hold X as the default binding).
2. Drag a rectangle over your belts, filters, lights, and platforms.
3. Release. Player-placed solids in the box go away.
4. Pipes stay. Switch to Pipe Remover for wet mistakes (Pipes and Pumps).

Use Ctrl replace (Demo Patches Hotfix 8) when you want to swap a conveyor for a Mark 2 instead of deleting a spine. Demolish is for wrong geometry, not for every upgrade.

Shift + drag marquee from the shortcuts page still selects; Demolisher is the delete pass. Do not marquee the entire factory unless you mean it — 0.5.4 made large deletes skip the expensive red-block orphan scan.

The 256-tile red-block rule (0.5.4)

Lantto is still working on a root-cause fix that touches many core paths. Until that is safe to ship, the Demolisher can remove red blocks, but only when the delete is 256 tiles or fewer. The extra scan for orphans is too costly on huge wipes.

Practical meaning:

• A small X-box on a red cluster in a hallway should eat the red.
• A screen-wide demolish of a finished wing may leave red tiles even though belts vanished.
• If red survives, shrink the selection and click again. Do not assume the tile is still immortal.

This is a temporary rule. When the engine fix lands, this page will drop the 256 number. Until then, treat 256 as the official cap from the 16 August 2026 note.

Puzzle doors and reset buttons

Red on puzzle doors is a different restore path: close and open the door. The note asked players to report if that fails. Do not grind a 256-tile demolish on a door if a toggle is the intended reset.

Puzzle reset buttons can no longer be deleted. If you already deleted one before 0.5.4, reload the save — the button comes back. Design puzzle attempts so the reset pad is not inside your “clear the room” marquee. Broader puzzle kit: Artifacts and Puzzles and Factory Tiers for anomaly rooms that used to soft-lock Tier 5.

What Demolisher will not fix

• World terrain that was never a player block (some red clusters are still “why is this here?” — community threads exist; do not invent a lore recipe).
• Pipe floods — wrong tool.
• Crashes — still Crashes and Performance and 0.5.3 logs. 0.5.4 did not replace the overlay launch flag.
• Lost drones under a sand pile — dig them out; demolishing the drop-off roof is a layout fix, not a drone respawn (Drones).

Factory hygiene

Delete test filters after you use the new Edit last placed flow so leftover Allow/Block cells do not sit on a live belt (Filters). Delete misaligned Shakers instead of layering a second diagonal on top (Shaker). Keep Collectors on solid floors — demolishing the floor under a wallet drops Gold into sand (Collectors and Lights).

When you rebuild, C copy / Ctrl+C / Ctrl+V (official beginner tip) is faster than redrawing a shaker bank you just demolished.

Related

• Update 0.5.4 — Full patch ledger, including save-browser icons and zoom binds.
• Keyboard Shortcuts — X, Shift marquee, Ctrl replace, zoom keys.
• Build Modes — Linear vs rectangular so you demolish less.
• Buildings Hub — Machines you are trying not to delete by accident.

Small boxes. Reload puzzles. Leave pipes to Pipe Remover. The red wall is a scan budget, not a skill issue.