Super Smash Bros - 282:44
Splatoon - 207:49
Xenoblade Chronicles X - 105:30
Mario Kart 8 - 28:48
Yoshi's Woolly World - 19:57

1) Xenoblade Chronicles X --> 99:04
2) Mario Kart 8 --> 92:56
3) Hyrule Warriors --> 51:46
4) Super Smash Bros. ---> 38:10
5) Super Mario 3D World ---> 33:46

Actually I might add some hours to other games, because I play some of them in my friend's house. So, Splatoon might be around 100 hours, and MK8 and Smash around 200 hours estimate.

Super Smash Bros for Wii U ---- 209:14
Splatoon ---------------------- 90:24
Mario Kart 8 ------------------- 82:00
Super Mario Maker ------------- 78:16
Xenoblade Chronicles X -------- 39:38

tagged. Xenoblade X was the most game I've played - 45 hours. Then closely followed by Splatoon, then Super Mario Maker.

Prior to that - Mario Kart 8, Hyrule Warriors. But the game I've mostly played on the Wii U last Spring was XC ~200 hours. :D

1. Xenoblade Chronicles X 221:07 

2. Smash Bros. 141:20

3. Super Mario 3D World 104:15

4. New Super Mario Bros. U 91:34

5. Splatoon 69:46

On a side note, Crunchyroll 245:05

Previous Edition:

[Netflix] - 730:54
[Internet Browser] - 388:29

1.) Hyrule Warriors - 213:14
2.) Monster Hunter 3 Ultimate - 206:51

[Miiverse] - 103:59

3.) Assassin's Creed IV: Black Flag - 91:19

[Nintendo eShop] - 82:38

4.) New Super Mario Bros. U - 64:56
5.) Call of Duty: Black Ops II - 64:01
6.) The Legend of Zelda: The Wind Waker HD - 62:15
7.) Assassin's Creed III - 57:32 
8.) Golden Sun: The Lost Age - 50:22
9.) Golden Sun - 45:53
10.) Mario Kart 8 - 42:40

Current Edition:

[Netflix] - 798:15

[Internet Browser] - 572:55

1.) Hyrule Warriors - 213:14

2.) Monster Hunter 3 Ultimate - 206:51

[Miiverse] - 104:40

3.) Xenoblade Chronicles X - 102:09

4.) Assassin's Creed IV: Black Flag - 91:19

[eshop] - 89:55

5.) New Super Mario Bros. U - 64:56

6.) Call of Duty: Black Ops II - 64:01

7.) The Legend of Zelda: The Wind Waker HD - 62:15

8.) Assassin's Creed III - 57:32

9.) Golden Sun: The Lost Age - 50:22

10.) Golden Sun - 45:53

I still have not completed Xenoblade Chronicles X. I plan to play much more of Xenoblade so expect some more hours next time around. Also, I fully expect to see Twilight Princess HD to chart next time. 

Super Smash Bros. has potential to chart, and so does Mario Mart 8. Having a bit of a shake up will be good. The list has remained largely the same.

Honorable mention: 

Internet browse: 441:51 (I use it to watch it t.v. shows and movies, is a great browser)

Is the same way in how I make all my other banners throughout this site..

Find a picture as a background and overlay text over it

[Internet] (892.:46)

1. Mario Kart 8 (90:54)
2. Assassin's Creed (85:12)
3. Xenoblade Chronicles X (76:10)
4. The Legend of Zelda : The Wind Waker (75:53)
5. Hyrule Warriors (57:48)

[YouTube] (54:43)

Previous

1.) Splatoon - 131:32
2.) Monster Hunter 3 Ultimate - 105:35 (Plus 255 hours if I include the 3DS ver)
3.) Hyrule Warriors - 72:18
4.) Super Smash Bros 4 Wii U - 69:26
5.) Mario Kart 8 - 54:21
6.) Xenoblade Chronicles X - 52:42
7.) Mass Effect 3 - 29:12
8.) Assassin's Creed IV: Black Flag - 27:18
9.) Watch_Dogs - 26:45
10.) Assassin's Creed III - 20:04


Current
1.) Splatoon - 169:38
2.) Monster Hunter 3 Ultimate - 105:35 (Plus 255 hours when 3DS ver is included)
3.) Xenoblade Chronicles X - 93:47
4.) Super Smash Bros 4 Wii U - 82:09
5.) Hyrule Warriors - 72:18
6.) Mario Kart 8 - 54:56
7.)Watch_Dogs - 30:48
8.) Mass Effect 3 - 29:12
9.) Assassin's Creed IV: Black Flag - 27:18
10.) Assassin's Creed III - 21:22


Biggest leaps were obviously Splatoon, Xenoblade X and Smash Bros. I also played more Watch Dogs.