In a unique twist to the beloved puzzle game Portal, a YouTuber named Marblr has successfully completed the game using a mod that inverts wall textures. This modification challenges the established gameplay by allowing only certain surfaces to be interacted with.

**Here’s what happens: ** Typically, players can only place portals on white concrete walls, but in this modded version, those surfaces are swapped with metallic textures, fundamentally altering how puzzles are approached. Marblr questioned whether it’s feasible to complete the game under these new constraints.

With the original structure flipped, some areas were made easier, while others became increasingly difficult. Marblr noted that the mod produced surprising results; certain chambers were straightforward, while others became near-impossible to navigate.

Portal Mod Image (Image credit: Valve, Marblr)

The full video of Marblr experimenting with the mod can be found on his YouTube channel, where he showcases the challenges and revelations encountered while playing through the game with this radical alteration.