Joined on 14th of July, 2011. I don't quite remember what version of the game it was that I started with - .8? .9? It was still a tiny bunch of parts, and the terrain was a poorly-textured cratery mess that danced and morphed like crazy as you flew over it. The planet was lonely and static - no moons, no other celestial body except for a single point of light for the sun hanging infinitely far away directly above the KSC - and no rotation, either. The dark side of the planet was glitchy and destroyed any craft that tried to land on it.
In a nutshell, the KSP was a bare glitchy proof-of-concept sort of deal. And yet, there was something about it that made me believe it would blossom into something beautiful. Maybe it felt like Orbiter and yet also like an actual game. Maybe the vessel construction reminded me of Spore done right. Maybe the Minecraft zeitgeist made me interested in watching this game develop right before my eyes and maybe even influence it as it did (mind you, the Early Access wasn't a thing back then, and neither were the weariness and wariness about unfinished indie games). So I bought the game as soon as preorders were available, and that was the best 6 euro I've ever spent on a videogame.