There are 10 different "worlds" in the game. The Beginning is the only one with only 1 difficulty (Normal) and the other 9 each have 3 (Normal, Hard, and Extreme). To unlock each level, you'll need to earn Gold Cubes. This will happen naturally as you go for
Passion for gold 
. Below is a list of each "world" and the additional features they bring to the gameplay. The features will carry through to each new world that opens, making "The Liar" by far the most difficult as it incorporates everything up to that point. Once you've completed at least one level in each of the worlds, the trophy will unlock. If you need a visual of any of these being done at any point in time, please see
Passion for gold 
for a video guide showing all the levels being completed with a Gold Cube score.
The Beginning:
This World is the basic/tutorial of the game. The instructions are simply to walk in the given direction. Go up when it says "UP", down when it says "DOWN", left when it says "LEFT", and right when it says "RIGHT". Easy enough.
The Negation:
The Negation adds the single negative instruction. Instead of just being told to go in a given direction, you'll now also be told to not go in a certain right. "NOT RIGHT" means any direction other than right, "NOT LEFT" is any direction other than left, "NOT UP" is any direction other than up, and of course "NOT DOWN" is any direction other than down.
The "Hard" difficulty in this world will add in the double negative, the instruction that cancels itself out. You'll still be working with directions, you need to pay attention to how many "Not"s are on the screen. "NOT RIGHT" means any direction other than right, but "NOT NOT RIGHT" means you need to go right. It's not...
not... right. This is the start of where the game starts to get fun (or confusing). For now, going forward, if there is an odd number of "Not"s, don't do the action. If there are an even number of "Not"s, do the action.
The "Extreme" difficulty in this world will add in the cruel triple negative. Now you have 3 negative-toned instructions to look out for. "NOT RIGHT" of course means don't go right. "NOT NOT RIGHT" as stated above is an instruction that cancels itself out, so you should do the action. Now you have "NOT NOT NOT RIGHT" which not only hurts to say, but probably also hurts your brain a bit. Use the recommendation mentioned under the "Hard" notes; an odd number of "Not"s means don't do it whereas an even number of "Not"s means do the action. So because "NOT NOT NOT RIGHT" has an odd number of "Not"s, don't go right.
The Void:
The Void introduces doors into the game. Starting on Normal, you'll notice there will (or won't) now be a ray of light on each side of the cube. These are the doors. You can only turn to any given side as long as this ray of light is visible. If there is no light, there is no door, so you can't turn that way. For this particular world, you don't have to worry too much about any missing doors as all 4 will be present all the time. It's simply introducing them for later. Outside of those, the levels play in the same sense as The Negation. "Normal" will only have the single negative, "Hard" will include double negatives, and "Extreme" will include triple negatives.
The Colorist:
If you can't tell by the name, this world introduces Colors into the puzzle. The doors introduced in the Void will either be White, Green, Blue, Red, or Yellow. The font color on the cube itself will also change. In this section, they won't go too crazy with it and the font will match the corresponding door, but that does change later in the game, so don't get too used to it.
"Normal" simply introduces the use of color. "BLUE" means go through the Blue Door. "NOT BLUE" means go through any other colored door. This section doesn't play too much with the mix-matching of the font, it just introduces you to the addition of color. You'll only have to work with single negatives as well.
"Hard" continues on with the introduction of color, but adds in the double negative. "NOT BLUE" is an odd number of "not"s, so pick any color other than Blue. "NOT NOT BLUE" is an even number of "not"s, so pick Blue.
"Extreme" will continue on with the introduction of color as well, but will add in the dreaded triple negative. Just as before, an odd number of "Not"s will have you listen to the instruction whereas an even number of "Not"s will require you to ignore the instruction. So of course, "NOT NOT NOT BLUE" will result in you choosing the Blue door.
The Logical:
The Logical adds in the use of "And" and "Or" within the instructions. If it's telling you "BLUE AND LEFT", you need to choose the Blue Door on the Left. If it's telling you "BLUE OR RED", you can choose either Blue or Red. Normal will take an easy on you and will, as before, just use the single negative in its instructions. This is simply to get you used to the additional conjunctions.
"Normal" will continue with the And/Or word play, but will bring back the double negative. This is where, imo, it can start to get a little confusing. Keeping the same recommendation as before with the Odd/Even number of "Not"s, you'll need to pay close attention to the conjuction being used. "GREEN OR NOT NOT GREEN" will require you to go through a Green door. "GREEN AND NOT NOT NOT RED" will tell you that you need a Green Door that is also Not Red.
"Extreme" will continue, but will bring back the triple negative and mix it with everything you've used up to this point. From "NOT NOT NOT NOTHING" to "NOT NOT BLUE OR NOT NOT RED", you'll really need to pay attention to the number of "Not"s used as well as the conjuction to make sure you're selecting the right door to go through.
The Color-Blind:
Remeber when I mentioned earlier that the font color will start to mix-match? This is where that starts to happen. Where the instructions will be "NOT NOT BLUE", which of course means go through the Blue door, the font color for "blue" will be anything other than blue. This is a test to separate what you see versus what you read.
"Normal" will simply be an introduction to the new feature. It won't go past single negatives, but will still incorporate the conjunctions in the instructions.
"Hard" of course will bring back the double negatives.
"Extreme" will follow suit and bring back the triple negatives.
The Impossible:
So you may have gotten used to the correct door always being available for you up to this point. If the instructions say "Blue", there's always been a Blue Door for you to go through. This is where that changes. This world introduces Impossible Instructions, one's that you simply can't complete. If there is no correct door to go through, do nothing. If the instructions say "Blue" and there are 2 Green doors and 2 Red doors, you can't complete the instruction, so just stand still and wait for the next instruction to appear. This is also where you conjunctions get a little bit more extreme. Whereas it might say "BLUE AND LEFT", you were clearly looking for the Blue door on the left. Now, you'll get instructions along the lines of "LEFT AND RIGHT". Well, you can't go in both directions at once, so this instruction is impossible, so don't do anything. It's imperative you're paying attention to the conjuction!! "LEFT
OR RIGHT" gives you a choice of the two, "LEFT
AND RIGHT" does not!!
"Normal" as before will just be an introduction to this new feature. You won't go beyond single negatives, but will undoubtedly need a few attempts to get the hang of reading the instruction, comprehending the colors and conjuctions, then making a decision to either complete it properly or stand still. All within a few seconds.
"Hard" will of course bring back the double negatives.
"Extreme" will bring back the triple negatives.
The Missing Door:
More doors! Or rather... less doors. The mechanic introduced in this World is the absence of a correct doorway. You've gotten used to there being a light/door on each side of the Cube, but now, every so often, one or more will be missing. If you get the instruction "RIGHT", but there's no light/door, then it's an impossible task so you can't do anything. If there is a correct light/door, then you can complete the instruction accordingly.
"Normal" will be throwing you into all of it, but will only include the use of a single negative.
"Hard" will include double negatives.
"Extreme" will include triple negatives.
The Following:
This world introduces a set or list of instructions versus just the one you're used to. Instead of the instruction saying "LEFT OR RIGHT", which of course you can go left or right on, you'll see something along the lines of "LEFT THEN RIGHT". "Then" is the new conjuction in play. Per the instructions, you'll go left first, then right second. Giving of course doors/lights are available to pass through. Some of the instructions will be 2 parts, some will be 3, and some will even be more. You need to pay attention to
everything. The lights/doors, colors, directions, negatives, conjuctions, etc.
"Normal" will "take an easy" on you (if that's even a thing at this point in the game) and will throw only single negatives at you.
"Hard" will of course include double negatives.
"Extreme" will include triple negatives and will be a hot mess.
The Liar:
This world takes everything you've learned/grown accustomed to so far and slaps a giant reverse on it all. You'll still get instructions as normal, but every now and then, you'll get one that has a cancel/do not do symbol on it. When this appears, you need to do the opposite of the instruction. So if it just said "RED", you'd go through the Red light/door. If it said "RED" but included the symbol, you'd choose anything but a Red light/door. You can still somewhat use the tip for the negatives mentioned earlier.
If there is not a cancel/do not do symbol: All odd number "Not"s result in "don't do the thing". All even number "Not"s result in "do the thing".
If there IS a cancel/do not do symbol: All odd number "Not"s result in "do the thing". All even number "Not"s result in "don't do the thing". So you're just flipping the logic when you see the symbol.
"Normal" tosses you into the deep end, but will only throw single negatives at you.
"Hard" will include double negatives.
"Extreme" will include triple negatives and will by far be the hardest level you do.