TL;DR?! Here's the quiz: http://www.itstoohard.com/puzzle/6aPjTQH6 That's all!

I will send the gift to the winner, and it's steam redeemable. Anyone solve this puzzle and comment on another private giveaway will be invited to this group and have the chance to win Metro 2033.
FYI, if you already have Metro 2033, you can join the private one for the price, so the puzzle is still worth a try.

Don't try to add me only ask for joining the group, or you will get blocked.

GL HF!

It will last for 1 month

If you have any questions,join the group chat and PM me. This is not necessary, when I tell someone something in PM, I'll add them to this thread as new hints.

steam://friends/joinchat/103582791432971281

Don't share your answers in group chat, I provide this only for you to PM me. Anyone who leak the solution will be excluded from this giveaway!

No Spoilers Allowed! You need to figure it out by yourself.

I went through all the steps myself and they works fine.

update1:
It's not hard to find.

update2:
Check link added No hints for this one. If you don't know what it is, just stop trying, it's useless. By the way, you can solve the puzzle without it.

When you get something partly random, not fully chaos, you're on the right way, just figure out why. (Déjà vu!)

update3:
Google is your friend. FYI, hints are in random order. Maybe you have already passed this one. :-)
There's another President of South Africa. Don't ask me why.

update4:
Have no idea about the string you got? It's part of an url.(for beginner only)

update5:
You think I'm talking about Nelson Mandela? No, that poor old man was in prison for years, he's not FREE.

update6:
Some of the comments are useful.
You get something doesn't belong to the string? Are you serious, Hector?

update7:
There's a connection between everything, do you notice the special one different from others?
Goo gle is your friend, ALWAYS.
Brute forcing and background knowledge are not necessary for my puzzle. If you have to guess something, I'm sure you have already missed some crucial things before.

update8:
This

update9:
Zodiac(not exactly, but similar)

update10:
Another big hint! Where? You need to find out. (Hinception: Links on this thread are useful.)

update11:
If you get trolled, you should go back and try another way.
Totally random errors means stop.

update12:
Hint added. Do you notice that? (One guy already found it, it's another Hinception.)

update13:
Finish part one? Then you have to check the links on this thread AGAIN. Find something weird? You're probably on the right way.

update14:
Read my first SG giveaway may help you a little.
Google is human's friend, but most people don't trust him. What a pity!

update15:
Hector used to be an airborne man, but now he's a barber.

update16:
If you still stuck on Q4, Google is a cake. Read update 3&5 and think again.

Final result: 1,237 players, 7 solvers. Congrats to the adventurers who solved it!

Solution added.