Portal is not only one of the most mechanically inventive puzzle games ever made, but it’s also one of the most elegantly crafted. Each of its Euclid-defying conundrums was built with surgical precision by Valve’s mega-brain designers, created to slowly and specifically introduce you to the power of thinking with Portals.
Central to this is where you can place portals throughout the game. Portals can only be opened on each test chamber’s white concrete walls, with black metallic surfaces denying your dynamic apertures in a fizzle of sparks.
These limitations are at the heart of Portal’s puzzling brilliance. But what would happen if you tried to play the game with all those surfaces switched? Such a harebrained scheme was recently hatched by Youtuber Marblr, who modded Portal to swap all the game’s wall textures around. Concrete becomes metal. Metal becomes concrete. “With the entire game remade using inverted textures, there’s an obvious question: is it possible to beat the game like this”? Marblr ponders.
To this premise, Marblr added a few extra rules and caveats. Although most of the playable surface areas in test-chambers are swapped, there are a couple of exceptions. For example, the metal surfaces beneath pools of black goo remain in situ. Since falling into the goo kills Chell instantly anyway, there was no practical reason to swap them.
Watch On
In addition, concrete walls with fixed portal frames are also left in place, as changing these would break the relevant puzzle chambers outright. Finally, given the high likelihood of this switch breaking Portal’s puzzle logic anyway, Marblr announces that “Any glitch or exploit is on the table as long as we stay inside the confines of each map.”
The results, as Marblr discovers, are surprising. “Some chambers were completely trivialized by the texture swap, making them even easier than the original. Other chambers did not fare so well and became borderline impossible to solve,” he explains.
The opening stretch of texture-flipped Portal demonstrates this vividly. The modded version plays relatively normally until Marblr picks up the first Portal gun—which only fires one type of Portal. In the original game, the next few chambers comprise entirely of concrete walls, so in flipped version they’re all metal, meaning there’s nowhere for Marblr to place portals.
Consequently, Marblr resorts to speedrunning tricks like “accelerated jumping” (jumping repeatedly to increase player speed and cross gaps) and “prop-climbing” (jumping repeatedly on a holdable object like a radio or a cube to climb up a wall) to progress. Yet once metal walls are introduced in chamber six, Marblr is suddenly able to skip entire puzzles. Since the walls at the end of the chamber are now concrete, he can just portal straight over to the elevator.
What’s fascinating about the texture flip is that it does, in essence, create a whole new puzzle game out of Portal. One that is far less balanced and requires detailed knowledge of Portal tricks and exploits, admittedly. But when you’ve played Portal as often as I have, this nonetheless has a certain appeal.
Marblr’s video is well worth watching in its entirety. But if you want to give flipped Portal a go yourself, Marblr’s modded version of the game is available over on ModDB. Obviously, don’t watch the video before playing if you want to solve the flipped puzzles yourself, though given the extreme nature of some of the solutions, you will probably find yourself consulting it regardless.
Best gaming rigs 2025