Kerbal Space Program with a litany of Realism Mods.
SETI: Among other things makes unmanned psacfelight the first step.
Remote Tech: Probes must maintain radio contact with the main base, realistic command delay. First order of business is to put 3 sats in triangular orbit.
USI Life Support: kerbals need supplies, if not they go inactive or die depending on what setting you chose. I chose to make them die
Deep Freeze: Allows Cryoing Kerbals for super long hauls.
Kerbal Construction Time: Ships take time to build
RealChute: Parachutes are more realistic, may actually make things easier in certain cases.
Stage Recovery: Allows deorbiting debris to be recovered instead of despawned if prerequisites (chutes, heatshields, etc) are met, without having to force physics simulation of them, important for money.
Final Frontier: Tracks what Kerbals did and gives them award ribbons, which is more fluff htan anything but w/e
RasterPropMonitor: Allows you to actually do spaceflight from cockpit view by adding glass displays to the ship,
like so (webM file).
For those in the know, the reason I don't use Ferram Air Mod is it lags like a bitch. I do use his joint mod that prevents loading explosions in game breakingly designed ships.
So yeah, should be fun, or a complete disaster. But at least a Mun Landing will be an accomplishment again.