10 Video Game Secrets That Unlock FULL Video Games
3. Metroid Prime/Fusion - Metroid (1987)
NES games are, and I mean this nicely, not the most advanced or data-intensive catalogue of games. By today's standards, you could fit the entire game catalogue on your phone, if you felt that way inclined.
So kudos to both Metroid Prime and Fusion for going out of their way to make you own not one but two separate consoles to unlock the game that started it all, the 1987 version of Metroid.
Not content with a simple "finish one game to unlock it", they made things much more complex. You need to finish Fusion, then link your Gameboy Advance to your GameCube to unlock a playable version in Prime. The thing is, if you're that invested in the Metroid universe, chances are you already own the first game in some capacity anyway.
Still, it was quite a novel reward for fans with multiple Nintendo consoles.
That being said, I think even Nintendo realised it was a bit of a faff, which is why follow up title Zero Mission on the GBA had a better solution to unlocking it: just finish the game.
Much easier.