Yeah... I've been a spaceflight fan for decades now. I started my gaming with Microsoft Space Simulator. I spent years just travelling around the solar system and galaxy. Most of the time on autopilot, but it was fun just to look at things, and on occasion fly a lander down to a surface somewhere. Then came the Elite sequels, Frontier, and Frontier: First Encounters. Autopilot kept me somewhat seperated from the actual physics part of it, so i never had to learn much and the comfortable fuel limit and thrust capacities of most ships allowed plenty of just "point and burn" when I did need to do manual control.
Then I got into Orbiter Sim. But even that(excepting the space shuttle), had somewhat fantastical thrust to fuel ratios, and the relatively tiny SSTO delta glider making it to low orbit with 20-40% fuel left and capable of making it all the way to lunar orbit from the ground with very careful planning. This is what truely started teaching me about orbital mechanics. I had to plan my own rendezvous. I had to know how to adjust orbits. I had to learn a ton of new terminology, because the instruments didn't dumb it down for me at all. But there were still instruments... and a basic, but functional autopilot. And it was somewhat forgiving of mistakes.
I can honestly say, Kerbal Space Program in it's early form... and even to an extent, today(although the map view and things like mech jeb have made a lot of the older problems a lot easier) is the toughest space sim to get a handle on, I've ever come across. It's also the one, because of that difficulty, and despite the slight simplicity and gameyness, that has ended up teaching me the most about space flight, orbital mechanics, even basic math. I'd been taught trigonometry in school, but I'd never had a reason to learn it until KSP. (And I still don't know it, like, off the top of my head, but I can claim to have actually used it now). It requires a careful touch to just hold the rocket together sometimes. It requires careful planning to get where you want to go, even it that's just into orbit. And probably toughest of all, it requires careful design, so your rocket DOESN'T fall apart and you still have enough fuel and thrust to get where you're going.
Also a set of working parachutes for the end never hurts.