joveian: I was going to say it couldn't be that long ago, and while the game page claims it was the changelog shows 1.0 as being on September 20, 2018 (and it wasn't quite finished then; they also mention it having been in development for 7 years, so I guess 2015 was the start of early access). They kept working on the main game for another couple of years after that, although it sounds like they mostly were working on the DLC starting a year ago.
Puchased instantly, although I see the version number is currently 1.4.0-5-beta, so I'll wait a bit before playing again (not hard since I'm currently hooked by Cyber Hook). I think they haven't had as heavily discounted sales before because there is a huge amount of content for the price (over 100 hours in the 1.0 game for me). Now they essentially charge the 10% off price with DLC, figuring those of us who already played it won't mind paying a bit more.
I have some complaints but overall I'd put it on a fairly short "best ever" list.
Sorry for my previous comment, GOG page stated that official release date is June 2015 (which is early access released) dafuq? When I've researched actual release date is September 2018 and 1st of all Early Access release should never used as Official release date. 100+ hours? I would happily paid for 15 bucks due to plenty amount of content despite it's couple years old but I purchase now anyway because it's best deal so far!
This game has been Beta for 3 years? I'm fan of indies and really hate early access because some of games has been stuck early access (alpha/beta phase) forever and never got actual release plus. If I have to choose between two of them there one really evil is AAA and another one lesser is Early Access but guess what? I rather not choosing at all because lesser evil is still evil!