TLDR: Check your antivirus software (Mine's BitDefender) and make sure it isn't stopping ES2 from writing to a temporary file.

I already figured it out, but I'm posting here in case someone else needs help with it. I didn't find any answer on the forum like this.

I was having this problem: I start the game, the SEGA splash screen comes up, then the Endless Space splashscreen comes up (the dude holding the lightball and the staff), then it all shuts down after about 2 secs.

I searched the forums and tried all these solutions.

I've tried running as Administrator

I've reinstalled

I've verified integrity

I changed environment variables as in here: https://www.games2gether.com/amplitude-studios/endless-space-2/forums/73-tech-support/threads/35283-game-crash-at-the-launch?page=1#post-293216

I've updated graphics drivers

I've run in compatibility mode through Win 7 and 8

None of that worked, but then I checked BitDefender, my antivirus. Sure enough it was flagging it as a suspicious executable because it tried to write to a temprary folder. I cleared the flag and it worked right away.

Good luck.

Upvoting this because people will most likely find this useful