This is harder than it sounds. Some years there were dozens of games that could have made the list, other years I couldn't think of a single game from the lists that I looked at that I enjoyed, and then there are years like 1990 where there had to have been better games but I couldn't find any that I liked better. There were years where I either didn't own a console or was playing older consoles or games and didn't experience the current games.
2018 -
2017 - Injustice 2
2016 -
2015 - Fallout 4
2014 - super Smash Bros. 3DS
2013 - Injustice: Gods Among Us
2012 - Diablo III
2011 - Portal 2
2010 - Tron: Evolution
2009 - Qix ++
2008 - Star Wars: The Force Unleashed
2007 - Portal
2006 - Marvel: Ultimate Alliance
2005 - Dead or Alive 4
2004 - World of Warcraft
2003 - Star Wars Galaxies
2002 - Mech Assault
2001 - Halo: Combat Evolved
2000 - The Sims
1999 - Pokémon Stadium
1998 - The Legend Of Zelda: Ocarina of Time
1997 -
1996 - Diablo
1995 -
1994 -
1993 - Myst
1992 - Wolfenstein 3D
1991 - Lemmings
1990 - Pit Fighter
1989 - Golden Axe
1988 - Battle Tech: The Crescent Hawk's Inception
1987 - Zelda II: The Adventure of Link
1986 - The Legend of Zelda
1985 - Paper Boy
1984 - Space Ace
1983 - Dragon's Lair
1982 - Dig Dug
1981 - Donkey Kong
1980 - Pac Man
1979 - Asteroids
1978 - Space Invaders
1977 - Combat
1976 - Death Race