Click the green flag to start. Listen while working on projects or just listen to it. You can also change Mario's color if you press Space. You can use a song or two and you don't even have to ask for permission first. Just remember that if you do use any, give credit to Nintendo/the original composers too probably.
Nintendo owns the rights to them, not me. The songs used are: Luma's Theme from Super Mario Galaxy Globe at Night from the Wii Weather Channel The End from Paper Mario Sheik's Theme from The Legend of Zelda: Ocarina of Time Distant Spring from Pikmin Rest Theme from Super Smash Bros Melee Piranha Plant's Lullaby from Super Mario 64 Goal Obtained from Pikmin 2 Snow from Pikmin 3 Dire, Dire Docks from Super Mario 64 Underwater Frigate Reactor Core from Metroid Prime Fi's Theme from The Legend of Zelda: Skyward Sword Star Way from Paper Mario Name These Children from Mother 3 Astral Observatory from The Legend of Zelda: Majora's Mask Current Capers from Donkey Kong Country: Tropical Freeze Memories from Xenoblade Chronicles