Falling back into my earlier mention of games that are fun for the sake of fun, I'll add Yoku's Island Express to this list. Granted the setting is very different than Headlander that I had discussed above, it still has a similar thought: make the audience smile.
Control a little bug, add in pinball mechanics in an exploration platformer, and make the world vibrant with writing the stuff of a decent Saturday morning cartoon (from the 80s, I guess, since cartoons air at all hours these days). It has a demo, so if you've seen footage and want to get a sense of how it plays, then have at it! It's right there for you. Go! Have fun! Feel like a kid.
Came here to mention Yoku's Island Express, but now that you have I'll shill Wandersong instead. Also designed to make you smile and cheer for the bard who wants to save the world. There's a few (very short) frustrating bits, but overall it's really fun. There's a quick look of it.