Let's see...

Switch:

BotW
Snipperclips
Blaster Master Zero (twice)
Wonder Boy (twice)
Super Bomberman R (at least three times)
Ultra Street Fighter II (does that even count?)
Arms (does that even count?)
Sonic Mania (three times)

3DS:

Kirby Tripe Deluxe
Kirby Planet Robobot
Phoenix Wright 2: Justice for All
Project X Zone 2

Wii U:

Shovel Knight: Plague of Shadows
Xenoblade Chronicles X
Project Zero: Maiden of the black Water (second time)
Paper Mario:  Color Splash

NES classic:

Double Dragon II
Castlevania
Castlevania II
Kid Icarus
Mega Man 2
Gradius
Metroid
Ninja Gaiden
Super C
Super Mario Bros
Super Mario Bros 3
Zelda
Zelda II

SNES classic:

Starfox
Mega Man X

Wii:

Kirby's Epic Yarn

PS3:

The Walking Dead: Michonne
The Walking Dead: Season 3

I know that! Happened to me with Final Fantasy VIII and IX.

LOT.

I looked at my profile to see if I could figure this out, I list the games I've completed in there. Although, some of these games I just continued from last year.

Dead or Alive: Dimensions for 3DS (4/5) -
Marvel vs Capcom: Infinite for X1 (3/5) -
Halo Wars 2 for X1/PC (4/5) -
Halo Wars: DE for X1 (4/5) -
Tekken 7 for X1 (4/5) -
Injustice 2 for X1 (4/5) -
Yakuza 5 for PS3 (3/5) -
Saints Row: Gat Out of Hell for 360 (3/5) -
Battlefield 1 (Campaign) for X1 (3/5) -
Assassin's Creed: Syndicate for X1 (4/5) -
Destiny: Rise of Iron for X1 (3/5) -
Call of Duty: Infinite Warfare for X1 (4/5) -
Destiny: Taken King for X1 (3/5) -
Street Fighter V (General Story) for PS4 (3/5) -
Call of Duty: MW Remastered for X1 (4/5) -
Donkey Kong Country Returns for 3DS (4/5) -
Forza Horizon 3 for X1 (5/5) -
Forza 6 for X1 (4/5) -
Resident Evil 5: Untold Stories DLC for 360 (3/5) -
Jet Set Radio Future for Xbox (3/5) -
Panzer Dragoon Orta for Xbox (3/5) -
Max Payne 2 for Xbox (2/5) - 

I chip away at my backlog on various platforms and I clearly I enjoy fighters. I actually completed a lot more than I assumed.

28 games beaten.
- 2 Mobile games
- 2 NES games
- 2 Wii U games
- 10 PS4 games
- 12 Switch games

In order of beating:
-The Last Guardian
-SteamWorld Heist
-Unravel
-Brothers: A Tale of Two Sons
-Skylanders: Swap Force
-Last of Us: Left Behind
-New Super Luigi U
-Bastion
-Clash Royale (as in reaching the top rank)
-Child of Light
-M.U.S.C.L.E
-Super Mario Run
-Blaster Master Zero
-Snake Pass
-Snipperclips
-The Legend of Zelda: Breath of the Wild
-Ultra Street Fighter 2: The Final Challengers
-The Legend of Zelda
-Overcooked
-Arms
-Super Bomberman R
-Inside
-Crash Bandicoot 1 remastered
-Binding of Isaac: Afterbirth+
-Has Been Heroes
-Graceful Explosion Machine
-Steamworld Dig 2
-Mario + Rabbids: Kingdom Battle

Top 5 best games beaten this year:
-The Legend of Zelda: Breath of the Wild
-Last of Us: Left Behind
-Overcooked
-Steamworld Dig 2
-SteamWorld Heist

5 Worst games beaten this year:
-M.U.S.C.L.E
-Super Mario Run
-Crash Bandicoot 1 remastered
-Brothers: A Tale of Two Sons
-Super Bomberman R

I've tried to beat Rocket League for over 2 years now but each season those bastards reset my rank.

I have beaten every game I bought this year. Also I started off the year with finishing FFXV from December 2016.

So in total:

FFXV

Nioh
Persona 5
Metro Last Light
Dragon Quest Heroes 2

FFXIV Stormblood

However with PS Plus I am working on

Just Cause 3
MGS Phantom Pain

You can see with my lack of funds, got to play some longer games aside from Metro (which was $5). I don't plan on buying anything else full price, but if a bunch of games on my list get price cut, I will buy them.

and close to beating Shadow Hearts on PCSX2

I'll look through my trophy list later and let you know. Tagged

Games from this year:

The Legend Of Zelda: Breath Of The Wild
Nioh
Resident Evil 7
Mario + Rabbids: Kingdom Battle
Mario Kart 8 Deluxe
Ultra Street Fighter II: The Final Challengers
Hey! Pikmin


Went on a bit of a NES bender this year and decided to try and beat most of the ones in my collection (and some I just bought) that I hadn't beaten before.

A Nightmare On Elm Street
Abadox
Adventure Island
Adventures In The Magic Kingdom
Adventures Of Tom Sawyer
Asterix
Balloon Fight
Battleship
Beetlejuice
Blue Shadow
Cabal
Castle Of Dragon
Castlevania III: Draculas Curse
Cobra Triangle
Conquest Of The Crystal Palace
Dr. Mario
Excite Bike
Friday The 13th
Ghost`n Goblins
Gremlins 2: The New Batch
Gun Smoke
Ice Climber
Jackie Chans Action Kung Fu
James Bond Jr.
Journey To Silius
Jurassic Park
Kabuki: Quantum Fighter
Karnov
Kickmaster
Kung Fu
Little Nemo: The Dream Master
Monster In My Pocket
Monster Party
New Ghostbusters II
Ninja Crusaders
Puzznic
Rockin Kats
Rollergames
Rush`n Attack
Rygar
Shatterhand
Star Wars
Swamp Thing
Sword Master
Teenage Mutant Hero Turtles
Teenage Mutant Hero Turtles II: The Arcade Game
The Incredible Crash Dummies
The Krion Conquest
The Rocketeer
The Young Indiana Jones Chronicles
Tiny Toon Adventures
Tiny Toon Adventures 2: Trouble In Wackyland
Totally Rad
Track & Field II
Werewolf: The Last Warrior
Widget
Wolverine
Wrath Of The Black Manta
Yo! Noid


and 3 SMS games

Aladdin
Asterix
Ghostbusters