Question is in the title. :)
Here's my list (in no particular order):
1. The Legend of Zelda: Majora's Mask 3D (3DS)
I had never played the original on the N64 and was thrilled when this remake was announced. This is definitely the most bizarre and unique Zelda game as it focuses more on sidequests than the typical dungeon solving of other Zelda games. It has a creepy atmosphere and is definitely one of my favorite Zelda games ever.
2. Metroid Prime 1/Metroid Prime Trilogy (Wii U VC)
I first discovered the Metroid franchise with Metroid Prime 2, so I had never played the first one (I could not find it in my country and the Prime trilogy was to expensive for me). I was very happy when Nintendo announced the Metroid Prime Trilogy for the Wii U VC and only for €10 to boot! The first Prime was a good game, but it's very overrated imo. After I played the first Prime I played Prime 2 again and that game is superior in just about every way. Still a good game though!
3. Metroid Fusion (Wii U VC)
While I did own a GBA I never bought any games for it... I only used it for Pokémon Silver... What a dumb kid I was. :p
I've heard a lot of hardcore Metroid fans complain about this game because it had story and was too linear, but I really disagree with those people. This is my favorite 2D Metroid game and has by far the best atmosphere of any game I ever played. The SA-X makes for a great villain and keeps you on your toes right till the end! The game has an excellent story, great pacing and smooth controls. It's also a very pretty game that aged well. I didn't care much about the soundtrack though. And this game actually does have exploration, I don't know why people say it doesn't.
4. Metroid: Zero Mission (Wii U VC)
This might just be the best remake ever made. I consider the original Metroid to be almost unplayable, but this game improves upon it considerably. This is one of the best looking games on the GBA (even better than Fusion) and it has the same smooth controls. I did like the pacing and story better in Fusion though, but this was still a great game. Especially the finale (which was brand new), one of the highlights in the entire Metroid franchise.
5. Mario & Luigi: Superstar Saga (Wii U VC)
I got this game for free on Club Nintendo and I was eager to try out a Mario RPG for the first time. This game had good graphics, funny dialogue/story and an interesting combat system. My only complaint about the game was that it dragged on for too long near the end.
6. The Legend of Zelda: The Minish Cap (Wii U VC)
Another great gem I missed on the GBA. Another game I got for free at Club Nintendo. And another game with beautiful graphics that aged well. This is also one of the few GBA games where I enjoy the soundtrack. This game was actually made by Capcom and they did an amazing job. I loved the concept of being able to change sizes and it was incorperated well into the Zelda franchise. Vaati was also an interesting villain instead of the usual Ganondorf story. Wouldn't mind seeing a sequel of this game on modern consoles!
7. Splatoon (Wii U)
The first new IP coming from Nintendo EAD since Pikmin! Was the wait worth it? YES! Splatoon is a breath of fresh air in an otherwise stale genre. The goal of the game's main mode is to ink the most territory (4 vs. 4 online mayhem). The game also has a unique singleplayer campaign that focuses more on platforming instead of shooting. The other multiplayer modes (Splat Zones, Tower Control and soon Rainmaker) are also a lot of fun! My favorite game of this year and probably my goty for 2015.
8. Captain Toad: Treasure Tracker (Wii U)
Since I live in Europe, this game only came out in 2015. This is a spin-off of Super Mario 3D World. In this game you take control of Captain Toad (and Toadette) to solve puzzles in small diorama like levels. A fun, if somewhat unambitious game. Graphics and soundtrack are amazing though.
9. Yoshi's Woolly World
This is basically a sequel to Super Mario World 2: Yoshi's Island. Without the annoying baby though! This is one of the most fun 2.5D platformers I've ever played and all the levels are made entirely of yarn! This is without a doubt the most gorgeous game on the Wii U. I definitely don't agree with the metacritic score this game got. It seems a lot of reviewers just rushed the game to beat it. This is an exploration collect-a-thon platformer and that's how it should be played. There are loads of secrets to find in this game and they're all hidden incredibly well. I've 100% this game and that's not something I do a lot.
