Currently, when hovering over a game in search results, a tooltip appears with detailed information about the game. This behavior annoys me and I'd rather not see those pop-ups. What options are there to disable this feature?

uBlock or compatible

! Store info tooltip for each product thumbnail
gog.com##product-tile-extended-portal

userContent.css file in Firefox or Stylus add-on for all browsers

@-moz-document domain("gog.com") {
product-tile-extended-portal { display: none !important; }
}

You, Sir, are a wizard! It works!
Just switched from AdblockPlus to uBlock Origin.
Now I need to learn the syntax of those filter rules. :-)

My last attempt to remove GOG sales pop-ups was only partially successful, probably because I tried to block these based on urls instead of page structure.

I'd like to suggest Stylus over Stylish if I may. Stylish hasn't been updated in years and it was reportedly gathering user data.

You're welcome. ABP set the standard for filter syntax, so a lot of it is the same. The interesting bits for me are the procedural cosmetic filters, especially :has and :has-text. Whoops, that was a typo. Force of habit, after typing that name on forums for years on end.