While writing this I have almost reached my 700th hour and that does not even include the ones I played offline, so I'm probably more near the 800th hour. Nevertheless, this is one of the greatest games I've ever played. It's difficult, yes. But not as difficult as it sounds or appears first. Watch Scott Manley's tutorials on youtube and with a little practice and patience you will be able to do all the cool stuff you can imagine. I don't want to misslead you, it can be a rly hard and a even little frustrating during the first couple of hours, but it's also so damn rewarding once you got past that initial learning courve.
So what does this game offer? A huge sandbox experience with lots and lots of content that has been build up and polished for about 4 years! You want to build a rocket? a (space)plane? a shuttle? a station? a moon (mun) lander? or a probe that travels across the whole system to reach the gas giant far out? Than do that! No one is stopping you! Your imagination is the limit, as much of a cliche that might sound like. But it's true and if you don't believe, watch showcases of people on youtube. There is everything from Star War's podracers to real life replica missions.
And if you fail a couple of times, there is nothing bad about it. The game manages to make failures fun. How? Cause you see stuff spinning, crashing and exploding in ways you couldn't even imagine. This is the unique experience of KSP that I've been enjoying with the greatest community I've ever seen. If you have a question, than simply post it on the forum. There are so many experienced vets out there that help each other and especially the new people with theire knowledge and skill. It's a rly unique group of people that has kept the forum alive ever since the buggy first steps.
You may ask yourself where the hell you might take the inspiration to build stuff after 100th of hours. The answer is simple. KSP is easy enough to be fun once you get used to the basics, while still being acurate enough to build real life replicas from the Apollo and Space Shuttle Aeras to modern missions and design like SpaceX's reusable boosters or Virgin Galactic's space ship one. It's all within the possibilities of this sandbox.
And if you want something more SciFi orientated? Then get a mod like interstellar or near future and you will get everything and more right at hand. Even for the type of players that enjoy a harder and more realistic simulation type of game there are easy ways to do just that. The moding community of this game is just huge. There is everything from physics driven algorithms that simulate hypersonic reentrie effects to adding whole new planets and solar systems. There is just so much content out there that you will literally never be able to see or play it all.
Long story short, after playing this game for years I sudenly felt a need, driven by nostalgia, to write this down and promote the best investment I ever did for a game.
I hope you will enjoy it as much as I did and still do! Cheers