I'll beat 3 more before the end of the year but here's what I've finished so far in 2018...

SNES
-Donkey Kong Country
-Street Fighter II Turbo: Hyper Fighting

GCN
-Star Fox Assault

WiiU
-Donkey Kong Country Tropical Freeze
-Bayonetta 2

GBC
-Donkey Kong Country

GBA
-Donkey Kong Country
-Kingdom Hearts Chain of Memories

NDS
-Final Fantasy III
-Kirby Super Star Ultra

3DS
-Pokemon Ultra Sun

PS1
-Tekken

PS3
-Ratchet & Clank 2 Going Commando HD
-Ratchet and Clank 3 Up Your Arsenal HD
-God of War HD
-God of War 2 HD
-God of War Chains of Olympus HD
-God of War Ghost of Sparta HD
-God of War III
-God of War Ascension
-inFamous
-inFamous 2
-inFamous Festival of Blood
-LittleBigPlanet 2 Special Edition
-Metal Gear Solid

PS4
-Fallen Legion Sins of an Empire
-Kingdom Hearts Final Mix
-Kingdom Hearts Re:Chain of Memories

PSP
-LittleBigPlanet
-The Legend of Heroes II: Prophecy of the Moonlight Witch
-The Legend of Heroes III: Song of the Ocean

Steam/PC
-Dragon Ball Xenoverse
-Prince of Persia Sands of Time
-Sonic Lost World
-The Legend of Korra
-Grand Theft Auto III
-Code of Princess
-Tomb Raider I
-Ys: The Oath in Felghana
-LEGO Batman The Video Game
-KARAKARA 2
-ARCADE GAME SERIES: Ms. PAC-MAN
-Serious Sam Classic: The First Encounter
-Serious Sam Classic: The Second Encounter
-Shantae and the Pirate's Curse
-PAC-MAN Championship Edition DX+ All You Can Eat Edition
-The King Of Fighters '97 Global Match
-Mega Man
-Mega Man 2

Completed
-Far Cry 5 (PS4)
-Kingdom Hearts 1 (PS4)
-Assassin's Creed Odyssey (PS4)
-Shadow of the Tomb Raider (PS4)
-Shenmue 1 (XB1)
-Sword Art Online: Fatal Bullet (XB1)

Started, plans to finish
-Red Dead Redemption 2 (PS4)
-Kingdom Hearts 2 (PS4)
-Jurassic World Evolution (PS4)
-The Sims 4 (PC)

Started, no plans to finish
-The Witness (XB1)
-Superhot (XB1)

Starting soon
-The Infectious Madness of Doctor Dekker (XB1)
-Home Alone 2 (Genesis)

Ongoing multiplayer games
-Star Wars Battlefront 2
-Overwatch
-Dead By Daylight

Not a particularly good year for me as far as completing games goes, spent alot more time playing multiplayer games this year. 

Monster Hunter World
Shadow of the Colossus
God of War
Spiderman

Games I finished (Until end credits roll)for the first time, counting DLCs also. If I sit down 2-3 more days before the year ends I should able to add a few more high profile games, if I make it I will add them before year ends =) 10ishof these though are complete fillers though.. I have like 650 NES cartridges at home and sat one night with a friend and a case of beers and went through som shitty games for the system hehe. Many of them took like 10-30 minutes... kids teaching games and so on hah. We had fun though ;P

Breakdown so far:
GB: 1
NES; 15
PC: 2
PS4: 6
SNES: 2
NSW: 23
Wii U: 4
XBX: 1

1 Mighty Gunvolt Burst Switch
2 Affordable Space Adventures Wii U
3 Nes Remix 2 Wii U
4 Art of Balance Wii U
5 Mighty Switchforce! 2 Wii U
6 Pan-Pan Switch
7 Heroes of Might and Magic 3 PC
8 Win, Lose, or Draw NES
9 Fisher Price: Perfect Fit NES
10 Snoopy's Silly Sports Spectacular! NES
11 Tiny Barbarian DX Switch
12 Teenage Mutant Ninja Turtles: Fall of the Foot Clan Gameboy
13 Fisher Price: Firehouse Rescue NES
14 Fisher Price: I Can Remember NES
15 Spot: The Video Game NES
16 Archon NES
17 Sesame Street ABC NES
18 Sesame Street 1-2-3 NES
19 Where's Waldo NES
20 Sesame Street: Big Bird's Hide & Speak NES
21 Taboo: The Sixth Sense NES
22 Jeopardy: Junior Edition NES
23 Resident Evil: Revelations Switch
24 Xenoblade Chronicles 2 Switch
25 Splatoon 2 Switch
26 Street Fighter 2 Turbo SNES
27 F-Zero SNES
28 End is Nigh, The Switch
29 Battle Chasers: Night War Switch
30 Wonderboy: The Dragons Trap Switch
31 Shaq Fu: A Legend Reborn Switch
32 Kirby: Star Allies Switch
33 Little Nightmares PS4
34 Overcooked: Lost Morsel PS4
35 Overcooked: Festive Seasoning PS4
36 Octopath Traveller Switch
37 Overcooked 2 Switch
38 Uncharted 3: Drake's Deception PS4
39 Gears of War: Ultimate Xbox One
40 Knights of the Round Switch
41 Hollow Knight Switch
42 The King of Dragons Switch
43 Armored Warriors Switch
44 Hollow Knight: Hidden Dreams Switch
45 Pixel Junk Monsters 2 Switch
46 Double Dragon NES
47 Ghosts n' Goblins NES
48 Diablo 3: Eternal Collection Switch
49 Mantis Burn Racing Switch
50 Earth Atlantis Switch
51 A Way Out PS4
52 Frostpunk PC
53 Celeste Switch
54 Horizon: Zero Dawn PS4

PC:

Dirt 3
Elder Scrolls Shivering Isles expansion
Fear and its 2 expansions
Fear 2
Condemned Criminal Origins
Rise of the Tomb Raider
Far Cry 2
Wolfenstein 3D and Sear of Destiny
Return to Castle Wolfenstein
Wolfenstein the New Order
Doom 2 and Master Levels
Quake 4
Medal of Honor Allied Assault and its 2 expansions
Battlefield Bad Company 2
Battlefield 3
Batman Arkham Asylum, City, and Origins
Assassin's Creed 2 and Brotherhood
Harry Potter 1,2, and 3

Gamecube:

Super Mario Sunshine

DS:

New Super Mario Bros.

Wii

Okami
Resident Evil 4
Harry Potter and the Order of the Phoenix
Super Mario Galaxy
Brawl Subspace Emissary

3DS:

Resident Evil Revelations
Ocarina of Time 3D
Pokemon Crystal

Switch:

Crash 1 (N Sane Trilogy) - easily the worst game I played to completion this year.

Add for PS4...

God of War, Horizon Zero Dawn, Resident Evil 7, Dragonball FighterZ, Persona 5 to the list.

Add for Switch...

Legend of Zelda NES, Smash, Wolfenstein 2, Starlink Battle For Atlus, Dragonball FighterZ (again), Donkey Kong Tropical Freeze, Super Mario Party, and over 40 hours of Warframe to the list.

Current backlog of games bought in 2018...

Red Dead Redemption 2 (PS4), Valkeria Chronicles 4 (Switch), Ys VIII (Switch), Diablo 3 (Switch), and Xenoblade 2 Torna (Switch), Pokemon Lets Go (Switch).  Plus more Warframe...

-Cossacks II: Battle for Europe.
-Passpartout: The Starving Artist.
-Portal.
-Portal 2.
-ExcaliBug.
-Neighbours From Hell.
-The Elder Scrolls. Skyrim.
-Neighbours From Hell 2.
-Axiom Verge.
-Impossible Creatures.
-Nanashi no Game (Nameless Game).
-Pokemon Omega Ruby. Regular Nuzloque.
-Blue's Journey (ACA NEO).
-Picross S.
-World Conqueror X (Victory with Spain).
-Soccer Brawl (ACA NEO).
-Highschool Romance.
-Might and Magic - Clash of Heroes.
-Zero Wing.
-Steam World Dig 2.
-The Coma: Recut.
-Calm Time.
-Splatoon 2. Octo Expansion.
-Chicken Invaders 2.
-Submarine Titans.
-Gun.
-Pokemon Sun. Regular Nuzloque.
-Pokemon Platinum. Random Nuzloque.
-Pokemon Blue. Random Nuzloque.
-Nightside.
-Lego Chess.
-Pokemon Black. Random Nuzloque.
-Endless Space.
-Skullgirls.
-Pokemon Blue. Regular Nuzloque.
-Deadly Creatures.
-Ashes to Ashes. Feeding the Flames of War.
-Victoria II.
-Picross S2.

So many nuzlockes... I would've beaten UltraSun as well, but UltraNecrozma is a murderous bitch and the game punishes grinding, so there's that.

Hmm, this is making me realise how many games I have accumulated this ear where I never quite got to the end. There's a fair few tat I got in 2017 that I cant remember if I beat ths year or last. Here goes

Pokemon Ultra Sun
God of War
Spiderman

Before the baby (up to May): Bonanza Bros (GEN), Toe Jam & Earl (GEN), Shining in the Darkness (GEN), EVO (SNES), The Lost Vikings (SNES), Magical Quest (SNES)

After the baby (May-Dec): BS Legend of Zelda (SNES), Dragon Quest (NES), Tearaway Unfolded 100% (PS4).

I meant to play through and beat Crystalis (NES) and Dragon Quest II (NES) but never found the damn time. Next year will hopefully be better...

Only game ive finished is Gof War, bought plenty of games just havent finished any lol