Mario Universe Super Mario Galaxy must be the most, least childish of the Mario franchise.

[ProjectilePuff]

Well, not least childish but it has that vibe that no other Mario game has, not even the sequel. I guess it's just... extremely climactic. The ending maybe the most craziest of all the Mario games and the way Mario loses lives in some levels are... creepy... namely ones like the instant killing vortex, being smooshed, sinking in matter, etc. and some galaxies just have, space in the background... making that kind of un-comforting for me atleast. I honestly don't know how to describe this without saying like over-exaggerated descriptions like "edgy" or "scary"...

 

[Planet Cool]

I wouldn't call Mario Galaxy "edgy," but it's definitely one of the best games I've ever played. The lighting, dreamlike atmosphere, grand orchestral score, and (unusually for a Mario game) emphasis on story and myth-making really make it stand out. Some people dislike it because it's so linear, but in my opinion, linearity is a perfectly legitimate design choice and I don't take any points off for it.

Also, you can play as Luigi for the first time in a 3D game.

 

[Xzsmmc]

It's still a pretty bright and cheery game. No worse than some of the **** Kirby pulls.

Also Galaxy 2 is better.

 

[Planet Cool]

Nonsense! Galaxy 1 is better! Galaxy 2 is longer and harder (heh, heh), and it has Yoshi, but it can't touch the original's atmosphere and epic scale. Epicness isn't measured in length alone.

 

[Tino]

Of course Super Mario Galaxy is the least childish of the franchise. That's what made it such a masterpiece.

 

[Depressed Gengar]

That's pretty debatable, considering Super Paper Mario exists.

 

[E-Mann]

There are some underlying themes behind Rosalina's past and connection with her being basically the goddess of the entire freaking universe, so yeah, it's the most mature game in the series, theme-wise.

 

[UcheD914]

I will tell you this much. That game was tough!

 

[Deleted member]

Super Mario Galaxy 1 and two are my two favourite games of all time followed closely by Super Smash Bros. for Wii U and I'll say childish or not those games wre amazing, levels , challenges, music was perfect they were amazing!

 

[Swamp Sensei]

None of the Mario games are childish.

They're family friendly. Not Dora the Explorer.

 

[Deleted member]

Swampsaur is right their family friendly, fun, and full of exploration that's not childish just welcoming and encouraging plus exciting!

 

[ElectroLightning]

What about Super Paper Mario? That was pretty dark.