The idea is simple, it's a 3D Action RPG, played in third person. It starts off fairly difficult, but by spending your money wisely [on all HP ups, in other words], and by getting the secret treasures, it's easy.
I destroyed the Golem's Arms, got it's secret treasure, defeated it, and then got the secret treasure on the Insect King bonus level, I finally wrapped up with the story mode of the Ruins.
Overall, I rate it a 10/10. Would honestly pay for the full game.
And seriously, Dat Boss Music.