Endless Space collection is free on Steam via the developer’s website.
There are also random other freebies, such as wallpapers, novellas, comics and artbooks.
The expiry date is unknown - It might be permanently free, it might not be.
Endless Space is a turn-based 4X strategy game, covering the space colonization age in the Endless universe, where you can control every aspect of your civilization as you strive for galactic domination.
How to get the freebies:
There is a little bit of faffing about . But it should only take you about 5 minutes to get the game for free.
Click this link: https://www.games2gether.com/.
If you have an account here, log in.
If you do not have an account, register and confirm an account. Then log in.
Go here: https://www.games2gether.com/profile/me/rewards.
You should do step 2 (log in) first before clicking this link, otherwise, you'll end up going around and around in circles due to the way the website is designed, since the website is still being built at this time.
Click “Link My Account To Steam”.
Then “Link My Account” on the confirmation window.
You’ll be redirected to Steam and asked to log into your Steam account as a security precaution.
You’ll then be redirected back to the website.
Click the Endless Space thumbnail, circled in red in the image below.
Click “Redeem It On Steam”, circled in blue in the image below.
If successful, the button will change to a confirmation message reading “Free content added to your Steam library”. You can now download and install it from Steam.
If you go back to https://www.games2gether.com/profile/me/rewards after getting the game, there are other free content you might be interested in if you scroll down a bit. Including wallpapers, novellas, artbooks, comics and so on.