I declare next week to Sci-Fi/Space - week!
To celebrate this occasion I will give away one space or Sci-Fi themed game every day from now until next sunday.
It's not that easy though, you have to solve puzzles first to find the giveaways.
Every giveaway leads you to a puzzle that leads you to the next giveaway.
All giveaways end at 7pm CEST (usually the time the Steam store updates), meaning you have a bit less than 24 hours to enter the first giveaway left, two days for the second, three for third, ..., and a week for the seventh and last giveaway.

All giveaways are already open, so if you manage to solve them all today you could already enter all of them.

Here is the link for the first giveaway, puzzle for the seond giveaway is found in the description.

Some rules:

• Don't spoiler the puzzles! This means: Don't give hints or solutions for a puzzle in the forum, chat, comments or anywhere else. This also applies to ended giveaways while the space-week is still running.
• Don't give away the links to the giveaways before the last giveaway ended!

Hints:

• Tier 1: Question #3 has (at least) three possible answers but only two of them will get you a 'correct'. Sorry about that.
• Tier 2: You don't need any knowledge about space travel, all you need is in the picture.

There's a link to somewhat Sci-Fi themed music in every giveaway page, they are NOT needed for solving the puzzles, so feel free to ignore them if you don't want to click them. :)

Puzzle ended:

• At least 275 people managed to click a link
• At least 157 people can count to five
  Correct answers: 1: Fritz Lang, 2: Stanisław Lem, 3: Ijon Tichy (or Professor Tarantoga), 4: HAL 9000, 5: Do Androids dream of electric sheep?
• At least 58 people left Earth behind them
  The giveaway code was hidden in the picture left of the rocket. Here's the picture with changed colours and saturation so it's easier to spot: picture
• At least 46 people speak an alien language
  The text was encoded in Caesar cipher with a 12step shift. A hint to Caesar could be found in the text, the easiest way to find the shift was probably by looking at 'S.O.S./E.A.E.' or at the steamgifts link.
• At least 55 people mastered the high art of internet stalking
  The code was the file name of the picture of Ghffovai's new computer in his pacebook profile's picture section.
• At least 42 people were determined to solve these puzzles
  The giveaway code was the determinant of the matrix seen in the picture. I chose the easiest matrix form, so everyone who got the hint could se it immediately but everyone who doesn't know anything about matrices could still get it by guessing (or looking it up on Google).
• At least 29 people made it back to Earth in one piece
  The last code was hidden in the picture: It wasn't just a picture but a zip-file as well. Inside it was a text file including the giveaway URL. Apparently opening it with notepad showed the URL as well.