Why is this free?
People get paid for stuff like this.
Every single instrument fits, even though there are lot of them, and they usually don't go together well at all. Even the volume levels are perfect. Most people make the guitar way too loud (or cymbals, which is an ear sore on headphones). Although this is a loop, it doesn't feel repetitive, because it is developing throughout, which is perfect for a video game.
I listened to this many times, and I could not find any imperfections, except perhaps the short length. This song is professional quality.