It’s very much in alpha stage and free do download right now. Tons of mods to add different parts to your rocket. Launch, achieve orbit, land on the moon! Or.. you can do whatever weird crazy thing you want to with whats available. I love this game so far, it looks like it’s going to be an interesting indie game.
I have fun making rockets in KSP! I tried some of the mods, but I like the challenge of building with stock parts only. I might go back to some of the parts packs for flight on Kerbin though. That seems like it could be super fun. I’m also working on escaping the entire Kerbin system at super high speeds with only stock parts!