Play Kerbal Space Program Realism Overhaul if you want a ... much closer to 'real' taste of how much more complicated and difficult an orbital flight is than a subortial flight, a lunar flight is than an orbital flight, an extraplanetary flight is than a lunar flight.
I'm not sure if it is still the unofficial motto of the mod... but it used to be 'if you cannot figure out how to install this mod, you will not be capable of playing it anyway', or something to that effect.
Oh how I wish the X-33 / VentureStar had actually worked out...
https://wikipedia.org/wiki/VentureStar
Either something like that, or somekind of... craft that has both a RAMJet and also some kind of rocket propulsion... that or a SCRAMJet that actually works... could maybe help get us to, or toward, at least an SSTO craft, or system.
Hah, or we can go full conspiracy theorist and find and publicize the anti gravity field generator equipped TR 3B in Hangar 18 or whatever, haha.