The reason is that it was on the 3DS. And the exposure the series has had via Smash Bros. Fire Emblem is a lot newer than Zelda and Mario. Which came at a time when Nintendo revolutionized home console gaming. They will always have their market. Fire Emblem was always a niche tactical RPG with a small following that gained some interest as their characters were added to Smash. People mention that “only” 490k units were sold on the Wii. How many of the Wii owners were interested in anything other than Wii Sports, Wii Fit, Mario, etc?
Fire Emblem deserves to be on the Nintendo Switch
Most people loved their Wii. But there was so much time spent marketing these gimmick games that games like Fire Emblem, Mad World, The Last Story, Pandora’s Tower, Xenoblade Chronicles, No More Heroes, and so on and so forth were overlooked.
We know lots of people that played their Wii a couple of weeks. And then it sat under their TV unused, many still are. So taking into account all of the above, 490k units for a niche game isn’t terrible.
As for the 3DS versions. Fire Emblem always sold better on handhelds. It was still a niche series but sold better there. As mentioned earlier in the post, Smash gave the series a hell of a lot of exposure, as did Nintendo Direct, as did Tokyo Mirage Sessions. Unlike Wii, people actually used their 3DS. People thought “Oh, we’ve seen those characters in Smash, we’ll give this a try”. They liked the game because let’s be honest, it’s probably the best in its genre. It had absolutely nothing to do with the child system.
Long story short, the game is selling because Nintendo decided to give it a push. Now only if they’d do the same with Metroid, F-Zero, Star Fox and everything else they can throw our way.
Source: Game Skinny