What instrument is used in the beginning? It sounds similar to a flute, but with more reverb. I... MUST... KNOW! 

Kirby & The Rainbow Curse: Original Sound Version

Burning Secrets

Mega Man Unlimited's soundtrack was composed by Kevin Phetsomphou (symfonikev), Philippe Poulin (MegaPhilX), and Yan Thouin (ThunderThouin).

I take no claim to Jake Kaufman's work, it's on bandcamp for free. Check it out:
https://virt.bandcamp.com/album/shovel-knight-king-of-cards-ost