In May 2022, a new version of the game titled "Twinsen's Little Big Adventure Classic" was added to Steam, replacing the version published by DotEmu and replacing their achievements with a new set.

I may update this in the future, but for now I will leave it up as most achievements listed here still match the new ones.

"Get the syrup in the pharmacy before going to Twinsen's house."

The pharmacy in Lupin-Burg (next to the telepod) is on your normal route as you try and get home after escaping the Citadel. At this point in the game, you won't be able to defeat the clone that arrives after the pharmacist sounds like alarm, but it's easy enough to grab the syrup and then run past them.

"Get the magic saber."

You will get this item as part of the normal plot. It is located in the locked safe inside Funfrock's HQ on Principal Island. You can access this area once you have obtained the fourth level of magic and the Red Card / Blue Card, regardless of whether or not the plot dictates you should.

"Unlock all the clover boxes."

Each clover box can store a clover leaf, each leaf will instantly restore your health if it drops below zero. There are a total of 3 extra clover boxes you can find.

The first box is found right after escaping from the Citadel, at the top of Lupin-Burg. Activate the sewer grate to descend into the sewers to find the box.










The second box is on an islet just off the shore of Pegleg Street, Principal Island. To reach it, you will first need to have gotten the Proto-Pack from Jerome on Proxima Island, since the bridge is destroyed and Twinsen cannot swim. Use the Proto-Pack to hover down from the beach, do not hover off the bridge.





After obtaining the second level of magic (Book of Bù), go back to Citadel Island. There is a tavern in Lupin-Burg (with a Grobo sat on the roof) that you may have visited earlier and overheard that the clones confiscated the cellar key. By this point in the game, they have come back to close the tavern. Simply beat up the Groboclone and you will then receive the key to the cellar. The clover box is at the back.

"Fire the cannon in the museum."

The Maritime Museum is located in Proxim City. You will first need the Red Card to enter the museum side door. If you try and enter by buying a ticket and going through the main entrance, the Rabbibunny curator near the door will recognise you and sound the alarm causing a Supergro to teleport in.

Once inside the museum, simply activate the cannon from behind. It might take a few attempts to find the right spot to stand in and there are no context icons to show you can interact with it.

"Finish the game in less than 4h."

Not much to say for this one. If you are familiar with the game, this should be a piece of cake. The bulk of time wasted is not knowing where you're supposed to go next and exploring. Once you have a rough idea of what items are needed to progress and how you get them, you could easily complete the game in 2 to 3 hours.

"Get into the meca-pinguin room."




In Proxim City, Proxima Island, there is a house next to the bazaar. Go into the house and speak with the Grobo who lives there. He will explain that he was accidentally sent a keypad for the Teleportation Centre by mistake and then gives it to you.







Once inside the Teleportation Centre on Brundle Island, look for a blue door on the right-side of the map. Right next to the door on the wall is an empty space to use the keypad. This opens the door to the Meca-Penguin room.








Note that the achievement description mis-spelt "penguin".

"Talk to the Star Wars fanboy."

You can find the Star Wars fanboy in the projection room of the Principal Island library (the room full of seats).

"Find the secret passage in the museum"

The Maritime Museum is located in Proxim City. You will first need the Red Card to enter the museum side door. If you try and enter by buying a ticket and going through the main entrance, the Rabbibunny curator near the door will recognise you and sound the alarm causing a Supergro to teleport in.

Once inside the museum, find the cannon. To the left of the cannon is a wall with a picture hanging on the left side and nothing on the right side. Activate the empty part of the wall and it will open, leading you to the roof of the museum where a Rabbibunny will give you some clovers.

"Unlock the second video of the ferry trip."

Simply come back later in the game and take the ferry. I'm not sure at what point this unlocks precisely, but certainly by the time you obtain your third level of magic this video is unlocked.

Your catamaran will follow you to your destination so don't worry about going back again.

"Have at least 500 Kashes in your wallet."

Most containers refill with their contents when you leave the map and come back. There may be other ways to quickly farm Kashes, but the quickest way I found was from the Principal Island library.

Enter the library and take the contents of the cash register (25 Kashes). The librarian will sound the alarm after doing so and a Quetch clone will appear in the doorway. It is possible to run out of the door before the clone gets the chance to attack you (the clone itself drops 3 Kashes or 3 hearts if defeated). Re-enter the library and repeat.

This might be useful for completing the "New record" achievement, saving time hunting for Kashes by stocking up a supply early.

Edit: An alternative spot to do this is when you reach the locksmith on Principal Island. Before proceeding to the Astronomer, you are able to enter and exit his store for 23 Kashes at a time and without having a guard appear (thanks DigDog).

"Unlock the 4 videos in which Twinsen gets a slap."

To unlock these videos, you need allow yourself to be sedated by a Supergro (the Groboclones in white). The four videos all show Twinsen getting slapped by Funfrock, but they have subtle differences.

One slap leaves a red mark, one slap leaves a bandaid and one slap leaves Twinsen with a black eye. The last slap Twinsen manages to block, but then still gets slapped again anyway.

• Upon starting the game in the Citadel, let the Supergro spot you or have one of the Quetch nurses sound the alarm.
  
  
• When you first arrive on Principal Island, make your way to Old Burg where there are plenty of Supergro's.
  
  
• After gaining the third level of magic (Sendell's Medallion), head back to Proxima Island and enter the museum. Have the curator by the door spot you and he will sound an alarm that teleports a Supergro in. Although you can get arrested here before you get the third level of magic, the video that plays is the same as from the Citadel before that.
  Edit: If this does not work for you, try getting caught after meeting the Astronomer on Principal Island (thanks g000nie),
  
  
• The last video will play as part of the plot when you are captured by Funfrock on Fortress Island.

"Finish the game."

Pretty self-explanatory. Defeat Funfrock, save the world, have a party and knock up your girlfriend.