Castlevania II: Simon's Quest is a platformer action-adventure created by Konami in 1987 for the Famicom and released in North America for the NES in 1988.
This is the second game in the extremely popular Castlevania series designed by Hitoshi Akamatsu. Compared to the predecessor, Simon's Quest has different gameplay. At first sight, it is a classic platformer, but when you start playing it, you realize the game is different. You can explore the world freely, and go back to places you have already visited (as you can do in Metroid, hence the term "Metroidvania" to define this kind of game). The gameplay is non-linear, with many RPG elements including levels and stats that advance with experience, inventory system, new weapons that you can purchase in the shops using the coins you obtained. Castlevania II is also one of the first games to have implemented a day and night cycle. During the night the game is more difficult, enemies are stronger and, as you can expect, shops are closed.
Castlevania II is not the most acclaimed title of the franchise, but it's the game that invented a genre, and whether or not you are a fan of Simon Belmont or Count Dracula, you have to try this action-adventure.