What 2021 Nintendo Switch game is the fifth main 2D Metroid entry?

The 2021 Nintendo Switch game that is the fifth main 2D Metroid entry is Metroid Dread.

Metroid Dread was released on October 8, 2021, and continues the story after Metroid Fusion. Nintendo presented it as the long-awaited next chapter in the side-scrolling Metroid storyline, and its development revived a concept that had originally been imagined for Nintendo DS in the mid-2000s.

MercurySteam and Nintendo EPD developed the game, with Yoshio Sakamoto serving as producer. It retains the series' exploration-driven structure while adding stealth-focused areas, where Samus must evade nearly indestructible E.M.M.I. robots until she obtains temporary weapon upgrades.

The five main 2D games commonly highlighted in Dread's marketing are Metroid, Metroid II: Return of Samus, Super Metroid, Metroid Fusion, and Metroid Dread. Metroid: Samus Returns is a remake of Metroid II, not a separate mainline chapter. Metroid Prime Remastered belongs to the first-person Prime branch, while Metroid Prime 4 is a different upcoming project.