Why would you do such a thing? It is annyoing for all visitors. Don't do flashing images for your game advertisement.
And if you have them in your game, give a disclaimer at the start. I see those all the time when starting a game. But never ever have I seen such a warning when buying such a game. At least not conciously, and surely not before entering the place where the game description was.
Do you know any shop that has these kind of warning messages before entering? Caution, beyond this point, ducks may be encountered. And some might even be in boxes.