Red Dead Redemption 2
Red Dead Redemption 2 has apparently achieved the biggest opening weekend of all time across all forms of entertainment. This at least what Rockstar is telling me and why would they lie about their own game release? Do you really think someone would do that? How distrusting you are.

So what does "biggest opening weekend of all time" really mean? Well, it means that Red Dead Redemption 2 had the biggest opening weekend in retail sell-through across all media types. It also had the second biggest launch (over three days) across all entertainment releases. I'm not sure what the difference is between being the biggest weekend and being the second biggest launch as it's designated here.
Rockstar Games® is proud to announce that the critically acclaimed Red Dead Redemption 2 has achieved the single-biggest opening weekend in the history of entertainment*. With over $725 million in worldwide retail sell-through during its first three days, Red Dead Redemption 2 is the second-highest grossing entertainment launch of all time next to Rockstar Games’ previously released title, Grand Theft Auto V, which achieved over $1 billion in retail sell-through in three days.*

*Red Dead Redemption 2 launched on a Friday so that its ‘opening weekend’ (Friday, Saturday and Sunday) is the same as its first three days, while Grand Theft Auto V launched on a Tuesday.

Oh.

Well, I guess that explains away the confusion then!

Anyway, it was also the biggest entertainment launch in 2018. It was the most pre-ordered game on the PlayStation Network. Speaking of the PlayStation Network, Red Dead Redemption 2 also had the biggest day one full game gales on PSN. It also had the biggest first three days full game sales on PlayStation Network.

Hey, not bad for such a small studio.