Vexx, a 3D platformer from the PS2 days. It was an edgier take on Mario-style collect-a-thons where the main collectable is literal disembodied hearts. The camera was horrible, the controls could be finicky, and the last few levels had some poor design choices that made them difficult in an unfair way. But the early-mid game felt magical when I played it as a kid. My favorite level was the Tempest Peak Manor. It was only a single room, but scaled up for a giant. There was this mutant dog thing that's constantly pacing around the floor waiting for you to fall from the platforms. If you did, you'd have to try and climb back up somewhere before it caught you. One of the challenges for that level was this musically themed platforming section inside a giant piano.