Unlock the following achievements by performing the corresponding tasks:
At the very beggining of the game, head left to find the glowing egg.
Altitude is Attitude
In Chapter 2 you'll find a broken tree you can push over to make a path forward. To the left of this is a rope that is nearly invisible due to the leaves in the foreground. Jump to this and climb it to reach the egg.
At the end of Chapter 11 you must climb a tall ladder that leads to the next chapter (after you lose your brain slug). Push the pipe on the ground to the right past the ladder and into the water under the pipe that isn't leaking water. Then, jump for the rope obscured behind a beam in the foreground. This will cause the egg to drop onto the pipe.
In Chapter 14 you'll come to a big elevator. Take the elevator to the second level and get off, then send it back down to the ground. From here, hit the button to bring the car back up and jump left onto the top of the elevator. Immediately jump to the rope hanging high up to the left and climb it to reach the egg.
Alone in the Dark
This one is tough: At the end of Chapter 14, after the part with the spinning saw blade and the two crates, is a dark passage or "cave" leading away from a ladder. If you move deep into this cave you'll fall to your death. However, you can actually leap an invisible pit here. You'll need to time your journey into the cave carefully, but after some trial and error you should be able to leap the chasm and get to this egg.
Climbing the Cog
In Chapter 16 you'll encounter a giant gear with a switch in front of it. Don't flip the switch. Jump onto the gear and ride it to the right until you reach the egg.
Right after losing the brain slug in Chapter 18, you'll find yourself on a conveyor belt. To turn back to the left and "backtrack" you'll need to push one of the boxes to the right for a bit and then climb on it. This lets you reach the edge of the crushing device to the left. Hang on the edge until the crusher recedes and then climb up and cross it to the ladder in the upper left. Up here is an egg.
Guided by Sparks
After the entire level stops rotating in Chapter 19, don't push the crate off the ledge. Instead, keep it near the electrified wall and use it to hop up onto a hidden ledge to the left. From here you can make a large leap to the right to reach the egg.
At the elevator in Chapter 21, move all the way to the ledge on the right. Then, tap DOWN to hang from the ledge and then jump to the right from your hanging position to grab a chain. Climb down to the egg.
Activate the first gravity switch just past the "HO" in Chapter 23. Move the crate to the right and stand over the switch. Then, when the gravity reverses, hit the switch a second time as you fall and move left to discover a hidden area. Pull the lever here for the final Achievement egg.
Where Credit is Due
Complete the game.
No Point in Dying
Complete the game without exiting the game or dying more than five times.