https://store.privatedivision.com/merchandise/buy-kerbal-jeb-plushy
It's great game to get kids into. What do we have to figure out in order to make it to the moon and back? Obviously it's a simplified model, but the concepts are there.
Yeah, it's a fun and accessible way to learn. It's simplified but it still has many concepts, it seems. I hope they kept a similar formula for the 2nd game. I saw a few videos on it and they seem to have done enough research and talked with scientists to get it right, for ex. regarding sci-fi elements like engines that are not really in production or even non-existent.
The game is more accessible than Reentry (more pics on Steam), which is a simulator. This one is pure madness, it even includes the original manuals from the Gemini, Mercury and Apollo programmes. It looks very well done too, but it's a completely different approach and there's no building involved.