Look, it's right there in the title. And yes, it's the whole theme, including the really complicated part in the middle.
This is YouTuber Tusko G.'s bit (find him on Twitch here) — recognizable video game themes done on kazoo. He performed Isaac's battle theme from Golden Sun last month, and then "Big Blue" from F-Zero the month before that.
Want more weird video game music? Hear the themes of Pokémon, Tetris, Super Mario Bros. and the Legend of Zelda played on bottles.