Crumbling tiles (referred to as cracked tiles by the cast, or "grey squares" by the Child) first appeared in Run 3. They have a grey texture with cracks on them. They are a pretty common tile, as they are sprinkled throughout the various levels in both Explore Mode and Infinite Mode. The first level that features them in it is Level 3.
In Level 3, you see some gray tiles with cracks. These are crumbling tiles. You find out that unlike normal tiles, they fall when you step on them! You can think of them as a "Step on it and watch it become a Hole" tile. Also, if you step on one that's in a group of crumbling tiles, the entire chain starts to crumble. This is implemented a lot in levels like Level 10.
If you use the Child, due to him being lightweight and his balloon, he can walk on crumbling tiles without crumbling them. They only crumble if he jumps off them. So, in Level 10, where it is made up of normal tiles and crumbling tiles entirely, he can win even if you leave it alone. That is why the Child is best when a level has a large quantity of crumbling tiles.
With careful timing, you can still walk on and jump off of crumbling tiles that have already fallen.
- Crumbling tiles were once ordinary tiles, but became gray and cracked from wear.
- Crumbling tiles are among the most important parts of the lore so far, as they seem to break almost every rule of the respawn system and barrier.
- If one remains calm, the Tunnel will not properly reset, and the crumbling tiles will not return, as seen in Bridge Building.
- If someone comes through, dislodges some crumbling tiles, and moves onto the next level, the crumbling tiles won't come back for awhile, even if someone else comes along and falls. This can be seen in the Angel Missions and Bridge Building, where the crumbling tiles you dislodge come back, but ones already gone do not.
- Amongst other measures, crumbling tiles will not appear in any Explore Mode level when playing Run 3 on an unapproved website.