With Metroid Fusion joining the retro games lineup of Nintendo’s Switch Online subscription this week, every mainline 2D entry in the franchise will be playable on the Switch. And if you’ve never played a Metroid before, it’s a great place to start. Fusion combines depth and accessibility, while also nailing all of the things that make Metroid so distinct — namely, its moody exploration and the feeling of being isolated in a dangerous place. Plus, it has a smartass robot and a terrifying villain....