If you have problems starting the game in any way, try the following:

• Disable any user made mods
  
• Verify the game cache (right click Stellaris in Steam -> Properties -> Local Files -> “Verify integrity of game cache”)
  
• Delete the …\Documents\Paradox Interactive\Stellaris -folder on your computer (make sure to backup any save files you may have in there)

If the game still won’t start after doing the above steps, then completely reinstall the game.Also, it seems some people had problems playing it fullscreen. Try setting it to windowed mode if nothing else helps (if you have a problem solved by this, please post a bug report in our bug report forum here[forum.paradoxplaza.com])Also: support.paradoxplaza.com may help you as well as our technical support forums![forum.paradoxplaza.com]

Edit// If you have problems getting to the game settings for whatever reason. Then try editing the ...\Documents\Paradox Interactive\Stellaris\settings.txt file with notepad

EDIT no 2// Also try restarting your Steam client

EDIT no3 You can also try starting the game by going to ...\Steam\steamapps\common\Stellaris\ and starting stellaris.exe by right clicking and selecting "Run as Administrator"

The stuttering issue is known and being worked on! Devs wrote about it on twitter, will be in the next patch!

If the above doesn't help, please use our official technical support forums: https://forum.paradoxplaza.com/forum/index.php?forums/stellaris-tech-support.942/ or contact support.paradoxplaza.com