To counter the glowing reviews others have left, it really depends what you want out of it and if you install mods or not (and if you do if all the mods you want work together). I don't use mods and want a more relaxing gamelike experience than a lot of folks here (but with lots of building and little micromanagment or random limitations just for difficulty) and it is meh in my opinion, although there aren't a lot of alternatives that are available DRM free and in some ways it is better than the alternatives. Look at actual gameplay, these trailers are useless for evaulating it as a game. Kerbals falling off the rocket is mildly amusing but they are mostly there to fly the rockets and don't really do much or have much to interact with. If they add ways to build stuff to interact with when you go somewhere (it sounds like they are) that would be nice.

There is a quite a bit of fun in building and launching a rocket. The learning curve is very steep but can be its own challenge if you like that kind of thing (I do). It takes quite a long time to do anything. Lots of people have posted interesting stuff that they built if you get frustrated and want inspiration. The wiki [0] has extensive documentation (except for the recent Breaking Ground extension so far) although the game much less so. Look at threads of the month in the Announcements forum for some amazing stuff people do with KSP [1] (seems like it would take an unreasonable amount of time to do any of that).

[0] https://wiki.kerbalspaceprogram.com/wiki/Main_Page

[1] https://forum.kerbalspaceprogram.com/index.php?/forum/11-ann...

Each version has lots of bugs [2] and some fundamental stuff was only implemented recently or not at all. DeltaV estimation and accurate maneuver planning are two things that only appeared about a year ago and are huge improvements. There is still no quick base game way to check the center of gravity of a plane with empty fuel tanks, although it won't fly well after a while if that is much different from the full center of gravity and you might not find out for a half hour or more since it takes forever to get anywhere and it is hard to balance a plane well enough to be able to use time warp. There are a few auto direction holding options if you have the right tech but nothing to keep your plane wings level with the ground or fly holding altitude. You can recover the parts of rockets that you land but you can't recover anything you separate before getting your main craft in orbit so you can switch focus to the debris (the huge fuel tanks that some people complain about in other comments are for those of us who want to recover everything and not leave space junk).

[2] https://bugs.kerbalspaceprogram.com/issues

I'd recommend both of the extensions if you are going to try it (although maybe try the base game first to make sure you minimally like it), particularly Breaking Ground that adds some minimal automation ability and the ability to get science by crashing stuff in to a planet or moon (this has bugs, although it should be fixed shortly). In career mode it takes forever to unlock all the science and almost none of it is at all related to building rockets, it is just doing the same few trivial things in a variety of locations.

Once you do get somewhere, on your home planet or elsewhere, there isn't really anything there, even with Breaking Ground that does improve it a bit. It used to be all terrain scatters (tree, rock, etc. looking stuff that you can go right through) and hills, now there seem to be two things you can interact with (also rock and tree looking things) that are the same all over a planet. So much of the fun is in the building and making up your own stories as you test a design. Or you can make stations and visit your stations.

I've played quite a few games due to poor health. Better in many ways IMO are Infinifactory (other than the horrible story), RollerCoaster Tycoon 3 (and 1 and 2 for that matter, with OpenRCT2 a nice requires-the-original-game upgrade mostly to be able to use higher resolution), and SimCity 3000 (unfortunately the GOG version crashes randomly after a few hours). Tropico (any version) and Surviving Mars also but they do the mandatory micromanagement and random limitations thing that I don't like (Surviving Mars more so but it has some good ideas too, like a number of camera options for taking in game photos). Theme Hospital (difficulty focused) and Banished (fairly building focused once you figure out the mechanics, although not that many layout options) are much simpler games but have some advantages from the game aspect and at least some building (Project Hospital looks nice and has more building but still has game breaking bugs nine months after release). Spore is also worth a mention; the building is mostly cosmetic and the gameplay has a bunch of issues, but it is still one of the few others that have a build and fly a space ship aspect (only with no atmosphere at all :/). OpenTTD (fully open source) and Cities in Motion focus on transportation building and are limited but decent for what they are. Widelands and Unknown Horizons are also fully open source builder clone games that are IMO improvments over the games that inspired them, Settlers II and the Anno series, although still not all that great. I hear Planet Coaster is good but it isn't avilable DRM free. There are a few more DRM free options but I get the impression they are difficulty focused rather than building focused.