We agree. As pointed out, we do have information in the tutorials, and we try to make the tooltips (when you hover a property or button) informative, and we occasionally write about features in our blog posts, but a more comprehensive and unified form of documentation would be very helpful (even for us on the team!).
We're in the early stages of planning and putting together a Wiki. We'll try to launch with the basics and then have the community help fill it in. This seems like the best way of moving forward for documenting something that continues to grow and change. 
I would say that if you want to use US2 as a space simulator and not a game comprehensive documentation is a must.
My initial testing of different simulations is very difficult to judge if they are accurate.
I would like to know how calculations are performed and what error sources there are. What underlying assumptions are being made ?
Some examples
I placed Venus Earth and Mars closer together around 1 AU to see if this would disturb their orbits ?
And also too see if the planets temperature would be habitable. I swapped Mars and Venus orbits.
I placed Earth around Alfa Centauri and also Jupiter. Result Jupiter was expelled from the system. The same result did I have for an older DOS based space simulator. Earth ended up being close to 100 deg C.
Particularly when it comes simulating climate and planetary temperatures I think it's imperative to know how results are calculated and what assumptions we have
Topic: I really think US2 should have a manual (Read 6875 times)
