I figure I may as well begin with the disclaimer. This game (at the time of writing this guide) has a vast array of painfully aggravating bugs. For myself, fortunately, there were very little CTD or completely game breaking bugs (Though some, such as the surely infamous furnishing related fps-drop, may as well be).

Long story short, if you're like me, you will love this game for it's peaceful environments and zen gameplay style, but hate it because its runs like dial-up from the late 1990s.

There is a bug that prevents you from getting achievements. It sucks, they're apparently working on it.
The way to get your achievement to start registering is pretty simple.
1. Before entering a level, go into the room adjacent to the one with the computer and tools etc. You'll see a big model landscape that is in fact a miniature train set.
2. You'll enter the room on the front-left hand side, on this side there is a large building behind the tracks (large in comparison to the other buildings close to it), hover over this with your cursor and you'll get the option to press "E" (or just left-click) to enter an interface where you can "build a train".
3. Build the mother-flipping train.
4. Come out of that interface and press "c" to accelerate the train that's now on the tracks. You should notice here that an achievement pops for building your first train.

Congrats, achievements are active. You can play the actual game now.
It may or may not require you to at least accelerate the train whenever you start up the game and load in.
I never took the risk, myself, and always played with the train set before jumping into a level (You don't need to do this for consecutive levels played in one sitting though).

A further disclaimer is that there are a number of discussions on the steam boards about having to take drastic measures to enable achievements/collect those you've accidentally missed already. Fortunately for you and I, the development team for this game decided to make the achievements tie in with the save game file, and further made the save game file almost completely readable, even to a non-programmer.
I'll get into this in more detail in the clean-up section of this guide, but if you're just here for the bug workarounds, feel free to skip ahead.

Note, getting all the achievements will take two playthroughs at least, though don't despair, only one of them needs to be time consuming. You can choose to do it in either order but I recommend doing it in the order as written, as it is more efficient in terms of tool upgrades.

YOU ARE NOT HERE TO ENJOY THIS RUN

No, I'm kidding, you can enjoy it, it's okay.

This run is straightforward. You get into a level, get to 50% completion as fast as you can, and get out. That's it. Don't even take time to look at the environment and DO NOT UPGRADE YOUR TOOLS. Don't even look at them on the cork-board, just get through those levels as quick as you can so you can get to the part where you actually have fun.

This run is entirely for getting one achievement in particular:


*EDIT* Mentioned by DeadBabyJuggler
This game may be beaten in one run, to do this, you have to skip the fast run and go straight to the fun run, BUT you cannot upgrade your tools until you've finished every level and gotten the achievement above. I found it easier to split the runs as the basic tools without upgrades take a lot longer to finish tasks with, but if you're determined not to play a second time that's the burden you bare.

Let's talk strategy. I know, it's a zen game, but it's buggy as all hell and you'll want to strategise to avoid those lag spikes.

The fast and hard rule to stick by is to leave furnishing areas until last. The biggest problem this game faces currently is the (seemingly) massive memory leak caused by furnishings placed by the player. Just avoid placing any items from the tab menu until you have done everything else in the level, then when you start doing the furnishing tasks get it done as quick as possible so as not to let the lag build up.
As I reached the end of my playthrough of this game, I found I lost interest in decorating (partly due to the lag, partly because it was my third time playing through as I did not have this helpful guide). This meant I found a pretty useful technique for decorating rooms quickly and avoiding the majority of the lag build-up.
The technique? Simple.
Stop caring.
Just buy what the game asks for in that location and wham it down anywhere as quick as you can without blocking yourself in.
I found moving backwards towards the room exit, looking at the floor and spamming the mouse button works quite well..

That's all you need for the first run. Just get one star in every level and then exit using the "finish" button found in the bottom right of the tab menu (Where you buy those pesky decorating items).

Now you can sit back and zen out dude. Take it easy, Breathe it in. DON'T PLACE ITEMS UNTIL THE END OF THE LEVEL. Go at your own pace. Just be one with it.

Just make sure you 100% complete every level. The game will ask you if you want to stay and explore more or leave the level when you have achieved this. If it doesn't ask you if you want to leave, you haven't finished working yet.

If you do this for every level, you will unlock the 15 achievements for completing each level and the 15 for completing each at 100% progress. This will also net you some extra achievements, fore example the one for when you first pick up a piece of trash, another for picking up 1000 pieces of trash, another for repairing train parts etc. These don't need explaining, you will easily get these naturally, especially if this is your second run.
The only notable exceptions are the star count achievements. These seem to be bugged, but we will deal with that at the end of the run if that is the case, so don't worry.

Also, in this run you can upgrade your tools! Yay! Doing so will net you infinite power (and less waiting around for train seats to be fixed..).


So, this time, you're going to want to be a little bit more careful with trash. There are two achievements that are a bit of pain to complete legitimately. (Seriously, I only just managed both by the end of my third playthrough).


So, the idea behind this one is to use segregated trash bins as much as possible! Also try not to destroy items using the crowbar or axe if it can be picked up and put in the segregated bin instead.

Every item you pick up will have one of four types:

• Glass: Green bottle icon
  
• Metals/Plastics: Yellow bottle and nut icon
  
• Cardboard: Blue cardboard box icon
  
• Mixed trash: Grey bin icon

The icon will show up to the right of the bottom bar that shows your inventory. All you have to do is put the item in the corresponding section of the segregated bin. It's colour coded and the symbol is shown on the lid of each section, so you really have to try hard to get it wrong.

Don't be afraid to empty the bin when it starts to get full either. It may cost $200, but you get at least $120 for each item put into the correct section, so drop two items in and empty it and you'll still profit.

Speaking of money, let's talk about the other achievement you'll be gunning for during this run:


This one needs you to earn a fair amount of money. It's not hard to get, and if you're recycling things as you should be, you'll get it without any trouble whatsoever.

That being said, feel free to invest in these four:


Simply buy a wall, floor, ceiling and train material from the tab menu and them use them on a wall, floor, ceiling and train respectively. Not all walls, floors, ceilings and trains can be painted but there are plenty across the levels to apply them to. Also you keep these materials across your savegame so if there isn't a place in one level try it in another!

Now let's talk side quests

The following achievements you won't get naturally but are easy to acquire:


This simply requires you to throw some trash into a bin. Use the mixed bin, it's easier.



Try to walk out of the bounds of the level and you'll get a five second countdown telling you to get back to the station. Ignore it, watch the countdown to 0, keep walking. Whatever you do, when it hits zero you'll be teleported back to the entrance for the level you're in and you'll get an easy cheevo. Congrats.



"Ooooooh a secret achievement! I bet it's super exciting!"
Nope.
On certain levels you will need to pump water out of a specific area using a pump. To get this achievement, all you have to do is THROW the pump at MAX POWER to the green indicator showing where it needs to be placed. It's pretty forgiving, so long as the pump is thrown upright. You just need to throw it in more or less in the right position.

So by now you hopefully have all of the achievements this game has to offer.

LOL jk. You probably have a few bugged out achievements that didn't pop. Sorry, it sucks.

So how do we deal with this?
SAVE GAME EDITING!

Like I mentioned before, the developers really didn't programmify the save game code, so it's surprisingly easy to disect what needs to be edited to get what you deserve (unless you're a cheaty-poo, in which case, shame on you.)


Let's start with the specific cases.



Simple fix:
1. Save your game under a memorable name, for example, "fixmybug" and then close the game.

2. Go to: C:\Users\{your_username}\AppData\LocalLow\Live Motion Games\TrainStationRenovation\Save and find your save file. E.g "fixmybug.save"

3. Open this file with some kind of text editor. I prefer using VSCode but even notepad will work.

4. Find the section with the heading "AchievementsData", there will be a section in here that reads:

Where X is the number of trash you've supposedly segregated in the game. Set X to 200 or 400 depending on what achievement you need. (If you need both I recommend doing it one at a time, I haven't tested if you will get both simultaneously)

5. Run the game, load the save and go into the tutorial level. POP, there's your cheevo!





Simple fix:
1. Save your game under a memorable name, for example, "fixmybug" and then close the game.

2. Go to: C:\Users\{your_username}\AppData\LocalLow\Live Motion\Games\TrainStationRenovation\Save and find your save file. E.g "fixmybug.save"

3. Open this file with some kind of text editor. (notepad is fine)

4. Find the section with the heading "AchievementsData", there will be a section in here that reads:

Where X is the number of stars you've supposedly collected in the games levels and Y the number of stars collected in the tutorial. Set X to 75 and Y to 5.

5. Run the game, load the save and go into the tutorial level. POP, more cheevo!

If ANY of the level achievements bugged out, or even if you just want to restart from the beginning with all your tools, stars and money you can do the following:

1. Save your game under a memorable name, for example, "fixmybug".

2. Start a NEW GAME and save it with a different name, eg "cheatynewgame" and close the game.

3. Go to: C:\Users\{your_username}\AppData\LocalLow\Live Motion Games\TrainStationRenovation\Save and find both of your save files.

4. Open this file with some kind of text editor. (notepad is fine)

For those who are unaware, so that this next step is easy to follow. The save game is in a format called a json tree. This means that each section and it's subsections are contained by curly braces, "{}". For example:


See how the curly braces enclose sections of data. The Main_File_data contains two subsections, "Player_Data" and "Map_Data" which are separated by a comma.
These two subsections each contain two pieces of data: their respective name and code.
Notice how the curly braces contain and segregate these sections and their data.

Fortunately the way these files are saved, the opening and closing curly brace for each section is vertically aligned so they are easier to spot. Bear that in mind as it will come in handy.

Okay, now we're ready.

5. In your NEW GAME save file, copy the entire section called "stationInfos"

6. In your COMPLETED GAME save file, replace the ENTIRE section called "stationInfos" with that from the NEW GAME save file. Be aware this section is quite long for a completed game so you may have to scroll through to find where the closing curly brace for that section is.

7. Load up your COMPLETED GAME save file, you will now be able to replay from the start, but this time with all of your stars, money and upgraded tools.

I hope this guide has helped you, and that this game hasn't ruined your zen, it's a lovely game, but it's also absolute trash.
Feel free to comment anything you feel needs to be added, if I missed anything, etc.