[2020] Full install process...

If the game has never run on this machine I doubt reinstalling will help, but to answer your question:

- move any valued save games elsewhere, and user_empire_designs.txt from /Documents/Paradox Interactive/Stellaris/ if you have made any custom empires or races.
- "uninstall" in Steam-Stellaris
- manually delete both the Steam/SteamApps/common/Stellaris AND Documents/Paradox/Stellaris folders
- re-install game in Steam, run a Steam Verify when done.
- add stellaris.exe to the exceptions list of your antivirus app; ESPECIALLY if you have Windows Defender, add it to the Ransomware "Apps Allowed Through" list.
- start the game with no mods active and test

In particular you need to make sure there are no files or folders left under either the Steam Stellaris or Documents Stellaris locations, before installing again.


For the launcher issue Please try this:

- exit the Steam app entirely
- uninstall Paradox Launcher v2 from the Windows "Apps and features" utility, if still present.

Delete the following folders if still present:

- C:/users//AppData/Local/Programs/Paradox Interactive/
- C:/users//AppData/Local/Paradox Interactive/
- C:/users//AppData/Roaming/Paradox Interactive/launcher-v2/
To see the AppData folder you'll need to enable View Hidden Items in File Explorer.

- run steam.exe as the Windows Admin user

- run the game from the PLAY button in Steam

IF that doesn't help, in this folder are some .log files:
C:/users//AppData/Local/Paradox Interactive/launcher-v2/
Please attach them here.  

From those logs the launcher is on at least 2020.11 possibly 2020.12, is that right? If so that should be okay and not causing an issue with the game.


For the game issue, In the game launcher please set Display mode to Borderless.

Add stellaris.exe to the exceptions list of your antivirus app; ESPECIALLY if you have Windows Defender, add it to the Ransomware "Apps Allowed Through" list.

Also if you have FRAPS or the MSI Gaming App or Rivatuner installed, disable it as it clashes with this game.

If that doesn't help:
DXDIAG is a program you run from a command prompt or the Windows start menu 'run' dialog box (or 'search programs' in Windows 7 or later). After running it will open a window and start collecting info with a progress bar in the lower-left corner. When it completes click the 'save all information' button and save it to a file then attach that file here.

Please attach your Documents/Paradox/Stellaris/settings.txt and pdx_settings.txt .
From your Documents/Paradox/Stellaris/logs/ folder, attach system.log .  

Does the launcher now show 2020.11 or .12 , or something else?

That dxdiag does not even mention this game, which is very unusual. Exit the Steam app entirely then run stellaris.exe manually from Windows Explorer. How far does it get, do you see any error now?