If the game seems a little short, try the additional challenge of not placing any God/dark Cubes! To be clear, you can still pick up God Cubes, just not use them by placing them into trees. Stuck? That's why this hint guide is here.
The Game is Not Enough Achievement Guide
Did You Notice?
Many puzzle games have a sort of "restrictive barrier" element — Portal and Portal 2 had their emancipation grills (a.k.a. fizzlers), Antichamber had matter destroyers, and The Talos Principle had the purple barriers and light blue forcefields, to name but a few.
Manifold Garden, however, is different — these obstructive elements are nowhere to be found, meaning that cubes can be taken freely between worlds! In fact, this is the main gimmick of this achievement. Only gravity hinders you, and it's often a weak hindrance given the repeating nature of the spaces you navigate.
But apart from that, there are also secrets in this game, and not just some dinky easter eggs, but special connections. Manifold Garden has full backtracking support, much like Antichamber, The Witness, and The Talos Principle, so even if you made it to the end, you can still discover much.
Without further ado, let's begin the journey (again).
Step 1: The Dark Wall
So, you've come out of the starting area and into the open for the first time in your playthrough, intent on not using any God Cubes. What now? You could solve the puzzles ahead, but first take a look around the sides of that infinite skyscraper. Turns out that all you have to do is take the staircase down — no falling needed — and witness this:
These dark walls can only be opened whenever you are in the dark world, and that means... yes, you have to pick up (but never place/use!) a God Cube.
Further down the staircase is this:
Just an ordinary door, and there are plenty like it later on. These doors can only be opened from the other side, and to do this first one you need to retrieve the first God Cube, and that means you need to solve all the puzzles ahead. Go do that...
...and then once you have the God Cube, walk back to the infinite skyscraper and down the staircase. Nothing more, really, other than to make it to the dark wall you saw earlier here:
It is now open! This means you can make you way to this location...
...and once you're here, let go of your God Cube and go hit the button. It's okay, really! You won't die, and nothing will reset except your location and that of the God Cube's.
Once you've done all that, a whole new world awaits you! You should be able to figure out what to do and where to go — it's just a matter of solving puzzles until you come to the second nexus:
Step 2: Cube "Walking" a Yellow Cube
From the above location, grab a red cube and enter the door that requires only a red cube. Soon you'll wind up in the location below. If you switch to the yellow direction, you might notice a thing:
Up close, it's a door that requires a yellow cube:
To get this yellow cube requires a little trickery, but I leave you with this hint: with 2 or more differently colored cubes (e.g. red cubes), you can "walk" a yellow cube up the wall of the puzzle seen in the first image of this section. You can get a yellow cube by progressing into the yellow God Cube area and taking one off of the tree there, or by using a cube on the color changer. Or if you're lazy, you can retrieve one of the yellow-green cubes.
After placing the yellow cube into the socket, move forward and solve the puzzles. No, I won't tell you how, but I will say that at some point you can expect to get the Homecoming achievement.
Progress to this first nexus:
Step 3: Sneaky Portal!
At this point, just as in any normal playthrough of the game, you can only progress through the door that opens with a button. Make your way to this location:
Normal progress leads to the red God Cube space — the one with the epicly long ball chute....but wait one second! I see a portal!
That's right, this room subtly leads to a different room — one containing a tricky ball puzzle. You can't see the whole chute unless you go elsewhere (it's a similar space that may require God Cube placement, but we don't want that...), so for convenience, here is the gravity color sequence:
Any other puzzles are fairly easy, and eventually, you'll end up back at the first nexus:
Step 4: Finding a Water Source
But this time, you have flowing water, and more importantly (for now), a blue cube. Go plug that into the socket that opens the door and move on through. You can easily reach the green God Cube area, but that is not why we're here! We are here to take the 5 blue cubes out of this area like so (falling is required — lots of it):
Now these can all be used to set up the waterwheel mechanism in the first nexus area and move forward to here:
Two things: first, don't solve the puzzle ahead, but instead just take the 3 blue cubes; and second, do you see the blue button in the image? This blue button is how you move forward. You'll find another waterwheel mechanism that opens a door, but where are you going to get the water from? It's not from the puzzle ahead, but from the previous area. More visually and specifically, you should have enough blue cubes to set this up:
(Mind the blue button — if it's in the way, a slight redirection should still work.)
Once you get through that door, you'll find a path to the orange God Cube area, presumably so that you can retrieve an orange cube. But why? En-light-enment to follow...
Step 5: The Answer Is in the Ceiling
Bad puns aside, the light in the nearby puzzle is more than just a light:
Like that one area in Antichamber, it deceptively conceals a couple of secret passages, as seen thus:
Down one of these hallways you'll find a socket for a red cube, and down the other, a socket for an orange cube. You should be able to work out how to get the orange cube from the previous step into this area — you don't even need to "walk" any cubes for this one.
Step 6: Advanced Cube Retrieval
Once you get through that door, you might wonder where you are (or if you are or have been observant, recognize it immediately). It's a space that leads to the purple God Cube space via the second nexus:
Before you didn't have the blue cube to progress, but now you do. Through the passageway, in the purple God Cube space, you can retrieve a red cube, and here's the specific location to get it from:
Yes, I know it's an optional area, but it leaves more open this way, should you want to backtrack and explore more.
Backtracking is simpler than you might think, but for the lost, check this out:
Also, to alleviate any falling fears, here's an image of the trust fall you're destined to encounter. Don't worry, the door's got you, and besides, you don't take fall damage.
As with the orange cube, no cube "walking" is required to get the red cube into this socket:
Step 7: The Trickiest Puzzle
The path ahead leads to this room:
If you hit the red button, you'll just be back at the first nexus again:
Not particularly useful at first glance, but across the way from where you first entered is another short hallway leading to this room:
Clearly you'll need a green and a yellow cube, or two or yellow-green cubes, or a mixture. A yellow cube would be extremely difficult to retrieve — this is because you'd have to get the yellow cube through a hole in its relative ceiling with little support. While not impossible, there is actually an easier way to do this — use a yellow-green cube, and bring a cube of a different color as a support.
This puzzle is key to getting beyond the main areas and into the final puzzles!
Step 8: The Other Ending?
The door from the end of the previous step should've dumped you into one of the finale hallways, where you can progress to this familiar, ornate location:
But before you move on, take a look behind this staircase — it's a doorway!
And not just any doorway either, but another portal!
Yes, this leads to the beams high above, but why? Here's why:
Well, you wanted to never place a God Cube, right? But you desperately need one to escape this dark madness! Go get it...do your thing. And...I'm sorry, because I know that I said I would be here and I would walk you through this, but, I think I need to go. And so I'm...just going to...Okay.
Do you remember seeing a large hallway as you're about to finish the game without placing a God Cube? There's another way into it from near the start:
It requires a blue cube, and here's the best place to get it from since there's this otherwise useless extra blue cube:
There's also a secret portal in one of the two archways along the opposite walls from the space leading up to the orange God Cube space (no screenshot for this one — you're on your own). Find that, solve the puzzles, and you'll be rewarded with a ton of new connections to old places.