Nah, it's a game which could be enjoyed with adults and kids alike. I have it, and I'm having a blast with it. And I'm sure plenty of 20+ Nintendo fans bought that game. It's fun, polished, and a twist to the shooter genre, something which is very Nintendo-like. They did it with Mario Kart. They did it with Smash. Not all of the 3M copies are kids, that's far from the truth. Parents buy to their kids what's popular, the console the majority of their friends have. And I'm sure that's not the case with the WiiU, it hasn't sold precisely well. So that's my guess to say that the people which keep buying the WiiU are, most of all, people who had any relationship with Nintendo in the past generations. 

If the main audience was returning Nintendo veterans, then pikmin 3 and dk should have similar sales to splatoon. After all, they've been around for nintendo much longer than Splatoon has. They're also just as if not more critically acclaimed then splatoon.

Actually, I would contend that Splatoon is not designed specifically for kids; it is accessible to kids, but pitched at a broad audience, including both kids and adults. Being a new IP doesn't mean it lacks appeal to Nintendo fans; it's competitive side for instance ropes in some of the Smash crowd. Contrary to stereotypes, Nintendo fans do not buy based solely on nostalgia, and colourful light-hearted games can appeal to adults.

If one were to survey Splatoon's player base, I'm fairly certain preteens would be a minority.

Pikmin actually sold about what you would expect given the Wii U's install base back in mid-2013 and it's not too far from Pikmin 2 sales according to vgchartz and if I remember correctly the psysical version of the game was discontinued as for DK the game got tons of backlash from the fans when it was announced for not being Metroid, so those 2 are not good examples to use as evidence that the Wii U's install base is mostly kids and not older Nintendo fans

Thats kinda sad considering how big DK is... or is suppose to be at least.

I would argue that splatoon is definitely made with kids in mind, but at that point we'd be in an endless argument since neither truly knows.

As for the Wii u base buying colorful lighthearted games, I would have agreed if games like Rayman legends and wonderful 101 had done better (we both know they deserved better)

Pikmin 3 sales (along with wonderful 101 sales) were admitted by Nintendo to be lackluster, so it was definitely not good regardless of the Wii u install base.

as for DK, that backlash was negligible when thinking about sales. No one refuses to buy a game because of what the developer COULD have made

I wasn't a fan of Wonderful 101, but Rayman definitely deserved better, on all platforms, though I suspect some Wii U owners bore it some resentment over the whole delay and loss of exclusivity thing. All I was saying was, one doesn't have to be a kid to enjoy these games. I think a lot of people in their 20s and 30s enjoy games like Mario Kart 8, Smash Bros, Splatoon, etc.

Dont you remember the backlash ubisoft received on miiverse, a lot of WiiU owners refused to support them after that and boycotted the game, it was a really bad business move on Ubisofts part not to release the finished game on Wiiu and make fans wait, we didnt mind it was going to other systems but should of treated it like a timed exclusive, thats the reason it did not sell as well on WiiU than it could have.

As for people wanting Metroid over DK this was a vocal group that didnt speak for all Nintendo fans, and i doubt it would of sold much more thanTropical Freeze, and dont get me wrong i love Metroid, and in all honesty we shouldnt even be discussing this matter as Nintendo should of made both games for the system.

1-Nintendo talked about lackluster Pikmin sales back in October 2013 and if vgchartz number are correct,they probably aren't,than without digital sales the game is actually only 230k behind Pikimin 2 that sold on an istallbase of 22 million so we can't say that the sales are lackluster for it and we don't know if Nintendo still think that it has been over 2 years since that statment was made

2-While yes some people won't refuse to buy a game because of not being what they wanted some will and how many times has Nintendo defended the development of a game,and DK also didn't have a good marketing campaing unlike a games like MK8 or Splatoon and we all know that would help the game alot

3-In this thread you mention Rayman and W101, Rayman didn't sale well anywhere because it come out around the time GTA 5 after being delayed on Wii U 2 weeks before launch and the delay wasn't small, so the game was destined to fail by Ubisoft and W101 and along with lauching close to GTA it didn't have any marketing campaing, nobody knew how to explain what the game was

4-Since this thread is about DK vs Yoshi using VGChartz numbers and you're utilizing Yoshi,Skylanders and Splatoon to show that a bigger part of the Wii Us installbase are kids then how did Xenoblade X sell over 500k with 2 weeks in the west and the lack of Japanese digital numbers, it has passed Skylanders and if it has good enough legs it could sell about has well as Yoshi