siebensus4 on 12 January 2022
Splatoon 2 reached 4 million. That's two times more than Breath of the Wild (1.9m) or almost two times more than Super Mario Odyssey (2.3m).
Splatoon 2 is in the same league as Mario Kart 8 (4.3m), Pokemon Sword/Shield (4.2m) or Super Smash Bros. Ultimate (4.6m) now.
I expect awesome numbers from Splatoon 3 in Japan. Not so sure if it can push hardware that much so late in its life cycle.
