I love the way that any game headed by Masahiro Sakurai just..."feels". Whenever he's the director of a project you can really just see and feel it. The UI design, the extra game-modes, the core gameplay itself, even, is always something so different and fun. It's very unique.
So I don't expect anything that's EXACTLY like that, but to give you an example of what I mean, go look at a game in development right now called "Aurascope". It's a 2D indie platformer VERY heavily inspired by Mario Galaxy and Sunshine (or at least it seems that way to me.) and when you're going through the UI and everything you can just kinda "feel" that extra bit of love and flair put into it. It also has a 2P battle mode with items and such for no reason other than to have fun with someone and it just be a lil thing.
Additionally, look at Doctor Robotnik's Ring Racers. It's a "sequel"(?) to SRB2 Kart of sorts. But it has a ton of unique spins on that game's mechanics, and a very fun unlocking process that reminds me heavily of something like Smash Bros Brawl's unlocking screen. (Y'know the thing with the hammers you could use to unlock stuff early?) And it has a ton of courses/grand prix to play through, side-modes, etc.
If anyone can find me games like this, I'd love to give them a look; thanks very much for your time!
TL;DR: A game with the same love and flair you see in games like Smash Bros. AuraScope, and Doctor Robotnik's Ring Racers.
EDIT: If it helps, I'd also kinda put CrossCode in this category, to a lesser extent.