A new space sim with a focus on Mercury, Gemini & Apollo just released yesterday on Steam as early access. I bought it and tried it out for about an hour. It focuses on realism, and you can go through the checklists and procedures. I'm liking the direction it's taking. The 3D cockpits are really well done. As early access, there are bugs and issues present, but that's to be expected of EA.

https://store.steampowered.com/app/882140/Reentry__An_Orbital_Simulator/

http://reentrygame.com/about/