I'm a professional astrodynamicist, and I can echo the other commenters about KSP. I used it to study in my undergrad. I don't know of any way to get a better

I'm a professional astrodynamicist, and I can echo the other commenters about KSP. I used it to study in my undergrad. I don't know of any way to get a better intuitive understanding of how the thrust directions affect trajectory, honestly.