I would like to be able to have more players in a Multiplayer party. At least 5 or 6 instead of just 4. I loved it back in the days of Titanquest that we were possible to play with 6 people. We had a multiple day LAN Party just playing Titanquest back then.
Sign - that would be great. 
I am like 96% sure we can add more with mods.
I think I have seen servers with higher player counts so yes, with mods it should be possible.
Not with “mods” but binary modifications.
Crate themselves ran a server with 12+ slots in the past to test.
Ok and how can i host a game with more players then?
Start learning assembly.
I dont think so.
Then its up to the Developer again.