I stop everything that I'm doing to play the latest major Portal mod that drops. This was no exception and is definitely in the upper tier of fan mods and you can feel that in the presentation. Revolution is quite a feat of the community. It's a very beautiful game, the outdoor segments are very nice and really feel like you're traversing the decayed wreckage of Aperture's surface. They even get Portal's writing and humor down pretty well without recycling jokes. I have two major complaints however: The game is functioning as a prequel to 2 and tries to explain the retcon of how GLaDOS was killed in the first game. That's neat and all, I can buy that, but the story plays out almost exactly beat for beat as 2: You wake from your slumber by a core who's rather dim-witted but helpful, when you get to the objective he reveals his malicious intentions, sending you to the underground where you meet another character from the past who helps you get back to the surface and fight your former friend, which culminates in a boss battle and portal-related disaster. I didn't mind it during play but c'mon. The other complaint is in the puzzle design. Some puzzles have you resetting the cube in order to progress, which is not how Valve designed their puzzles. Resetting the cube is the equivalent of restarting the puzzle and that is so ingrained in me that I was stuck on one puzzle for 15 minutes because the idea of resetting the cube never occurred to me. To me, Reloaded is still the best Portal mod campaign I've played because that felt like a proper evolution in the mechanics of the game the same way the gel was in 2. This is more story driven than that was and it succeeds in what it sets out to do, which is be a fan Portal 1.5. I think this is as close to Valve tier quality as I've seen from the community and if you're champing at the bit for more Portal content this is pretty great, my prior complaints notwithstanding.