Adding a game with out the game creators consent

[it's-a-me-aiman]

Okay so, Imagine you were me, and wanted to add a game that you absolutely adore. Your first action would be; Ask the creators consent, But what if I was like; "Naaaah! of course they would let me do that!" And then just added the game with no hesitation. Would that be dumb of me to do? If so, what if I do ask the creators consent but they didn't respond? What would I do now?

(Also before anyone asks, this is exclusively for more modern 2d games/ fangames, So no games from the 1990's or 2000's )