I've split the achievements in a couple categories to better group them and explain how to obtain them. The categories are:

• Power-up Achievements: Related to the different power-ups you can find throughout the map;
  
• Exploration Achievements: Related to exploring the map and its collectibles;
  
• Boss/Endings Achievements: Related to the two final bosses of the game and the different endings;
  
• Challenge Achievements: Related to full game challenges or the game's completion.

Gain the ability to climb on walls

Gain the ability to stand on blue blocks

Gain the ability to dash forward with a burst of speed

Gain the ability to jump again in while in the air

These first 4 abilities are the basic ones that are required to beat the game without any skips or unintended methods. You should not have any issues finding them as they're not hidden at all.

Gain the ability to freeze water under your feet

This ability is found in the hidden level at the bottom of the map that is opened with the complete amulet. You'll need the 4 basic abilities to reach the entrance and all 6 shards of the amulet. In the next section of this guide, I've included a map with the locations of all 6 shards, and the entrance to the hidden level.

Ascend and find the ability to dash through enemies without taking damage

This ability is found at the end of the secret parkour area at the top right of the map. You'll need all 4 basic abilities as well as the water freeze ability to acquire it without much struggle. To enter the secret parkour area, get on top of the lone island at the top right of the map, then double jump while going to the right as far as you can. Once again, there's a map in the next section with an arrow showing where to jump to.

Buy the bubble shield from the shop

The bubble is a great extra ability found in the shop in the middle of the map that protects you from one hit and is replenished at a checkpoint. You'll need a minimum of 32 total fruits to purchase it (10 for the Emerald Key and 22 for the Bubble Shield).

Collect every single fruit in the game

There are 50 total fruits in the game, enough to buy out the shop (10 for Emerald Key, 18 for Amulet Shard, 22 for Bubble Shield). If you're struggling to find any of them, there is an in-game item that will reveal to you on the map the locations of every fruit you missed in a room you have already visited. That item is at the very beginning of the game, and it requires the double jump to reach.

Unite all shards and restore the amulet

There are 6 shards to collect throughout the map, and they're pretty well hidden and hard to find. One of them is found in the shop, and another requires the red key found at the top of the map, which can be pretty tricky to reach. Further below I have included a map that shows the locations of all shards, as well as the key and where to use it.

Thank you for the music my man

To get this achievement, you must find the hidden room located inside the crashed ship at the top left part of the map. You'll need the basic power-ups to reach it. The location is marked on the map below.

Explore every room in the game

Here's a screenshot showing the full map with all rooms explored, as well as collectibles and areas of interest:

• Red: Shard locations and arrows showing how to access them;
  
• Orange: Red key required for one of the shards. The X is the key and the O is where to use it;
  
• Purple: "Note Worthy" room location;
  
• Blue: Location to place the complete amulet and access the hidden level;
  
• Green: Direction to access the secret parkour level. If you have difficulty getting on the tiny island from below, start on the white circle, jump while going to the right, then after the screen transition double jump to the left.

Get the normal ending to the game where you repair your ship and return home alone

To get the normal ending, simply beat the final boss (your old shipmate) at the top left of the map without fighting and beating the secret boss first. His attacks are not that hard to predict and dodge, but having the Bubble Shield can save you from losing an entire attempt. You'll need to hit them 9 times total, three in between every stagger, and you can only hit him during the spikes attack when he sits still.

Defeat the old witch

To find this boss, go towards the regular boss but head right instead. You'll need the water freeze ability to reach them. This boss is quite harder than the regular boss, but it also has more openings for damage:

• Right after his slash attack across the ground, you can jump on their head;
  
• After the 4th ground slam, they will stay still for enough time to jump on them;
  
• While it is spawning many damaging areas in the arena. The boss will not stop this attack until you hit them.

It takes a total of 12 hits to defeat them: 2 hits to break the shield and a third to damage them, and this cycle repeats 4 times, the last one being a 2nd phase where attacks are faster and harder to dodge. Defeating this boss is required to 100% the game. After defeating them, you'll only be able to access the good ending by beating the regular boss, meaning that you won't be able to get the regular ending after defeating the old witch without starting the game over.

Save your only remaining friend and return home together

To get this achievement, first defeat the old witch before fighting the regular boss. From what I can tell, the fight is identical to the regular ending's.

Achieve 100%

Here's the list of actions that contribute for achieving 100% completion, from what I could tell:

• Collect all 50 fruits;
  
• Explore every single room in the game;
  
• Defeat the old witch

The 6 amulet shards and the abilities don't directly increment your completion percentage, but are required in order to reach all rooms in the game, so you'll have to collect them anyway.

Beat the game in under 20 minutes

This is a pretty short game, so finishing under the 20 minute time frame shouldn't be too difficult for you. The main things you'll need are all 4 basic abilities and at least 10 fruits for the Emerald Key in the shop. Additionally, you could try to get 32 total fruits for the Bubble Shield in the shop. This would take some extra backtracking after getting Double Jump, but could save you against the boss. This is risky though given the time restriction, so I would not recommend it.

The order I would recommend for the abilities is Wall Jump -> Blue Blocks -> Dash -> Double Jump, as this minimizes unecessary visits to rooms with harder platforming. Take more risks earlier in order to get fruits so that after you activate the Blue Blocks and while going towards the Dash, you can stop by the shop and buy the Emerald Key. There are just enough accessible fruits in between the start and the Dash location for that in this route. Practice makes perfect, and make sure to have the boss' attacks down before getting there.

Beat the game without dying a single time

The hardest achievement in the game, naturally. First things first, No Death Mode is not required for this, finishing a run in Normal Mode with 0 deaths also grants you the achievement, and I would also recommend using Normal Mode anyways for practicingg in case you die near the end and want to keep going for a personal best. The same route I described for the speedrun achievement should be the easiest here as well, but this time around I would highly recommend getting every possible easy to reach fruit in order to buy the Bubble Shield.

I managed to identify around 35 or so total fruits that are reachable along this route with minimal danger and essentially no backtracking through hard platforming. The hardest of them are near the very beginning of the run, meaning dying to them would only cost a couple minutes. The Bubble Shield is essential because, while in Normal Mode, if you lose the shield, you can quit out to the menu and continue the run, without losing the 0 death run. Practice the entire game before attempting this achievement, but I trust you'll be able to achieve it.

Thank you for reading this guide all the way to the end! As someone who played the original Geometry Dash this started as, I'm absolutely thrilled this became a real, fully fledged game!