I discovered this game last year. It also has Newtonian flight physics, though not orbital mechanics. Trading, combat, mining, seamless planetary landings (with atmospheric flight and turbulence, but with smaller-than-real planets), exploration, missions, station building, faction control, etc. Quite nice. Also can have online multiplayer though the community is small.
http://www.starwraith.com/evochronlegacy/
https://www.youtube.com/watch?v=2hW1cUDArkg (original trailer, though HUD elements and some other things have changed since then)
A fair bit of customization can be done. For example, I changed all the flares to get rid of the long horizontal lines, added more to my HUD, etc.
I like the way the maneuvering controls work. Hold the stick a certain amount and your thrusters stop firing once you achieve the desired rotational speed, then you rotate freely until you return the stick to center or move it more to increase the speed. Your main thrusters are a two-way engine, so you don't have to flip around to slow down. When I wondered why you don't see the reverse thrust, the developer provided a detailed diagram and explanation as to how he imagines the engines to work! He's very active with the players.