Gosh, they grow up so fast, don't they?
Zelda II: The Adventure of Link and Castlevania II: Simon's Quest are both celebrating their 35th anniversaries this month.
The former is the direct sequel to The Legend of Zelda and was released in North America on December 1st, 1988. It received positive reception upon launch, but more contemporary analyses of the gameplay garner slightly more divisive opinions. It features a vast overworld similar to the first game but would shift perspectives when tackling enemies, a feature that seems rather odd for a Zelda game. In fact, it's not entirely unlike Castlevania II itself!
Speaking of which, we're almost certain that Castlevania II launched on the same day, but we've been unable to verify this with 100% accuracy. We do know that it launched in North America in December 1988 though, nearly two years after its Japanese release on the Famicom Disk System. Much like Zelda II, Castlevania II is divisive amongst fans, with many pointing to the backtracking and day/night cycles as particular points of contention.
That said, without the design choices made in Castlevania II, it's probably likely that classics like Symphony of the Night might never have come to pass. So there you go.
So while neither game enjoys the universal acclaim that other entries in their respective franchises have managed, there's no denying that Zelda II and Castlevania II are important touchstones in gaming history. Both can be played on Switch too; the former via the Nintendo Switch Online service, and the latter through the Castlevania Anniversary Collection.