Orbiter is underrated compared to KSP, which is recommended nearly always when the topic of orbital mechanics comes up. Orbiter is not only free(ware) but also a fairly realistic space flight simulator.

Perhaps the realism/implicit difficulty is the reason it's less recommended?

KSP is enough to give you an intuitive understanding without the gritty details of which switches in which order.

That said I did just pop up a video of orbiter to check what I remember... And the oceans are solid.. at least KSP has some model of water landings?

Is it as hilariously fun as KSP though?

Windows only. D':