Decorations are decorative 'items' automatically generated on empty walls, floors and ceilings. They can block portals, gel or protrude from surfaces so there will be a blacklist item to block them. They do only generate if enough space is present for them, and the right surface colours.

Examples:

• Cutout tiles (walls and ceilings), plus panels which fall off surfaces
• Panels hanging out of the wall, or moving around
• Plants
• Wreckage and rubble
• Construction materials (Old Aperture)
• Wiring
• Damaged wall segments

Here's an example of the current simple form (not modifying walls).

The set of decorations will be changeable like music, quotes, etc.

The main issue is that these will likely break maps, putting a panel arm on a tile that portals need to be placed on for example. You'll need to add blacklisting items to those tiles to keep them clear. The amount generated will be adjustable, though with 0% = off.