When the world opened up to Chell, is was gold. It was almost fake gold, such a stark contrast from the decaying labs she had finally managed to escape below. The sky was clear and blue and the land a sea of golden grass, everything clean and new, open to her for exploration, with her trusty, albeit a bit crispy, Companion Cube at her back.
A few more steps out into the real world and she quickly realized something was wrong. For one, the grass seemed to be covering the tops of what looked like city buildings. For another, she was pretty sure that was an actual ocean over the next grassy ridge.
If it wasn't an ocean, it was a huge lake, because she couldn't see the other side of it. Chell looked around some more and saw nothing but ocean water and sand and golden grass, and the ruins of a human civilization. The shed she had once taken to be a secret laboratory hatch out in the middle of nowhere now looked like a rooftop opening that had been hastily covered up.
For a full day Chell walked, directly away from the beach, until she hit another. She tried going to sleep hungry, but the ground was hard and the air uncomfortably warm. Instead she tried cleaning her Companion Cube off, and found a note hidden in a removable panel. It was typed up, and held only the words "Animal King Takeover," with a pair of ghost eyes topped with a crown.
She was eventually captured by the Animal King's drones, half-starved and on her way back to that rusty hatch that now seemed her only hope for survival. It wasn't so bad, she soon learned, living underwater, but it wasn't very comfortable either. The mutated Ghost Shrimp had been kind enough to build air-filled passageways for their human subjects, but the constant threat of a break and suffocation was unpleasant.
And there was the added sensation of realizing she had spent most of what she could remember of her life trying to escape into the real world, and now she was trapped again. Trapped with other humans who seemed less human than the robotic AIs she would willingly admit she wanted to get back to.