I'm surprised Katamari Damacy hasn't been mentioned yet. Both that game and its sequel, "We Love Katamari," have been remastered in recent years (in fact, the sequel just came out last week) and they're a joy to play.
The game has all that OP mentions... Quirky art style, awesome music, simple tactile gameplay, and just overall a relaxing and fun time.
Interesting. I played the original ages ago (like, as a Japanese bootleg before it got localized for Western markets) and only played the remake last year... Can't say I noticed a difference in difficulty, and hunting down 100% Achievements was QUITE the challenge.
"We Love Katamari" DOES feel off to me, though. Like, I get kind of frustrated at the density of objects, and it's never a feel I've experienced with the original or its remaster.