Some people asked me to post the solutions to find the secret wagons after the end of the giveaways.
So here it is.

• Train 1
  Nothing special here, you just had to click on the given link.
  Also no secret wagon in this train, sorry for the people who looked for it :)
  (I couldn't think about anything else after brainstorming about the whole scenario)

• Train 2
  The link was for this image.
  It shows the platform 5.
  So if you are going to page 5 of this topic, you'll find the link to Train 2 on the first comment :)
  Secret wagon : AaaaaAAaaaAAAaaAAAAaAAAAA!!! for the Awesome
  To access the secret wagon, you just needed to click on the little . of the Star Ruler wagon.

• Train 3
  Easy access by a given link :)
  Secret wagon : The Last Door - Collector's Edition
  Obviously, the weird things are the numbers instead of the usual Next wagon.
  Most people, if not all of you, know what to do with these numbers.
  Just need a binary to text converter and use it on each binary number to find TDFCv/.

• Train 4
  Well, on this one, you got this image.
  So what to do with that ? :)
  The train is hidden.
  Just have a look to the source code of the page and you'll find it.
  Secret wagon : Dracula 4 and 5 - Special Steam Edition
  To find this one, there was a suspicious description here :)
  Well, you just needed to go back to the first wagon and once again have a look to the source code.

• Train 5
  The given link directed you to a ItsTooHard puzzle.
  Well, can we call that a puzzle ? :)
  Just need to answer Yes everywhere.
  At the time i write this, i have these statistics (^_^)
  Then you are given the link to Train 5.
  Secret wagon : Euro Truck Simulator 2
  That's the reason why the train was so late this day :)
  I really wanted to find an idea for the secret wagon.
  So on each train wagons, there was a link to an image about the game.
  But the images were a little edited :)
  In order : A b A Y h /

• Terminus
  Nothing special here, just click and enter :)

• Topic secret wagon : Alice: Madness Returns
  Well, that was obvious :)
  The links for each train in the table were a letter.
  You just needed to wait and get them all when all 5 trains were available to find the topic secret wagon.

• Trip secret wagon : How to Survive - Storm Warning Edition
  Normally, you can find all the letters in the description of the last wagon of each train.
  In order : c t U 9 R
  In the last wagon of train 5, there was also a link to a ItsTooHard puzzle.
  It is optional, it just gives you the / to add to the letters.
  To find it, you just needed to answer Yes to the question Do you still like trains ?.
  It looks like one of you doesn't like trains anymore (^_^)
  (You could also bruteforce it, if you missed one train ;)

• Group and Whitelist wagons
  Well, simple, if you were on the list, you could enter.

To finish, here's a little summary of the giveaways (i know you don't care, but i like the table feature :)

I had fun making all that and i hope you enjoyed the trip :)
I will send the gifts to the winners as soon as possible in the next few days.

Have a nice day ♥

Yay!! It is my birthday (in few days actually)
Yay
Yay!! I am one year older...
Yay

As the tradition wants, here's a little something for you, Steamgifts Community.
I know that you like travelling.
So here's a trip in 5 parts around Steamgifts Land.
Catch the trains and take a seat in the wagons you like.

Trains can be late.
You can go through the wagons, but depending on the class of the wagons, you will be able to sit or not (I know, it is bullshit and the driver is a total jerk). (^_^)
There are also some private compartments, feel free to enter if you are in the list.
Rumors say that there are secret wagons, but it is only rumors.

During the trip, you can listen to some music.
The playlist is made by Kraken (I hope it is ok to put it here).

That said, enjoy the trip and have a nice day ♥

Edit : Thanks for the ♥ and don't be sad if i don't reply to your comment (^_^)