The rules state that we may not change the game - that’s perfectly clear during the voting period but as this is my first-ever itch.io contact i simply missed the screenshot feature on the site.

Am I allowed to add some screenshots to the game page (of course without modifying the game in any way!) or will that disqualify me?

Thanks in advance for the answers :-) Cheers!

I'm sure you can update the game page and submission page.  Adding a screen shot should be ok.  You are allowed to fix bugs in the game is my understanding but can't add new features or make a new game.