Trains?

https://www.steamgifts.com/giveaway/XXXXX/

Replace XXXXX with the 5 digit code.

Also, it doesn't matter what is written after the 5 characters and the / where the game name is. So, you can just open an existing giveaway, replace the 5 characters in the URL, and leave the rest. I find that to be the quickest way, especially if they provide a link with other parts of the URL changed.

you can also open some random giveaway and replace the 5 digit code with the one you got from the puzzle.
no need to change the name of the game as its converted automatically

lol
edit: just read what AllTracTurbo above me wrote... oops

🙄・・・

zelgh magic guide to basic sg puzzling | UPDATE October 2017
There are countless puzzles in SG.
And sometimes there are 5 letters, sometimes there are different numbers of letters, so you might want to read something like this at those times.

Please note that there is a penalty for inadvertently writing the answer to a puzzle in the discussion of the puzzle, or for including an unintentional clue.

Revealing Puzzle Information or Games 24 hours
Revealing Puzzle URLs 3 days

🧩 Ja━━||Φ|(|´|Θ|`|)|Φ||━━il!!!!