ELI5 for the 1.2M number:

Hitting 1 million signatures is the final goal but that’s counted after the signatures are verified for legitimacy. With a petition like this, 20 to 30% of the signatures are stricken from the final count. So having a large buffer above the 1 million number is essential.

People buy games, but some games have been set up so they stop working in a few years. The petition is asking the EU to make it clearer if/when the games stop working, or to make it so the games never stop working. The petition passed it’s goal, but they’re worried that some of the signatures aren’t real, so they’re aiming to get a bigger number so even if a lot aren’t real it’ll still pass the needed number.