My friends and I have played GC3 on Steam many times since the game was released. We just tried to launch a game yesterday and it won't work.
Everyone can join the game lobby without problem, and everyone can choose their race. When I host, I can set the AI enemies and everything else no problem at all. We all click "ready," and then I click "start." Initially, it seems OK. The first few loading things pop up [destroying galaxy, loading custom ships, building galaxy] and then it crashes to Windows. Steam remains open, but GC3 is gone--completely crashed to Windows. There are no error messages, no debug files; there's no indication whatsoever about what is wrong.
We tried again today, and we tried our hand at troubleshooting the problem by doing the following:
1. Disabling all anti-virus/firewall stuff
2. Direct tunneling via Hamachi
3. Uninstalling and reinstalling our games
4. Switching off all of our DLC and just trying to launch the vanilla version of the game
5. Ensuring that our PCs were completely up to date
6. Ensuring that Steam was completely up to date
7. Ensuring that our game files were completely up to date
8. Having one player host a multiplayer game without any other human players in the game, then saving the game, and then loading the saved game and having the other players join and take over previously AI-controlled slots. (This is the only way to play online when using the Crusade DLC; so we figured we'd give it a try even though we weren't using Crusade at the time. Later we did also try enabling Crusade and it still didn't work).
After that, we tried launching the game without some players to find whether or not one of us was causing a problem for everyone, and it turns out that everyone else can host and launch the game no problem. It's only me that causes the issue; however, to be clear, when it crashes to Windows, it crashes to Windows for everyone.
Now, during step 8 (above) we did notice a quirky thing. Whenever I tried to join the game after another player had saved and uploaded the save file, I was totally unable to select any of the AI or do anything. It would sort of freeze and then eventually kick me back to the main menu without any error messages or debug stuff.
It happens without any explanation at all and it is infuriating for me because I am diehard GC3 player. Why is this suddenly happening to me, and how can I fix it?