What 5 games defined 2010-2019 for you? Your number 1 game gets 5 points, your number 2 game gets 4 points, etc. After everybody counts down their five decade defining games, I'll tally the totals and update at the end of the year.
As an example here's my top five decade defining games...
1. Dark Souls (5 points)
2. Breath of the Wild (4 points)
3. Stardew Valley (3 points)
4. Poke'mon X/Y (2 points)
5. Skyrim (1 point)
Darks Souls was the game that brought back the idea of "hard isn't a bad thing". It spawned it's own genre that in turn influenced a ton of other games. Dark Souls isn't a Rogue Like, but Rogue Likes wouldn't be as popular if Dark Souls hadn't come around and shown people how fun a hard game could be.
Breath of the Wild redefined open world games, and gave Switch a huge boost. The checkmark lists of tedium from other open world games are gone. Having to Bethedsa jump over mountains is gone. Now it's all about discovery, interesting locales, and gliding to your destination. Also physics work across the entire game, letting you just create your own solutions to problems.
Stardew Valley showed us what a single developer could do. And it is the pinnacle of the building, crafting, survival genre.
Poke'mon X/Y because it redefined competitive Poke'mon play, and brought the main series into 3D.
Skyrim because it pretty much defined the open world genre up until BotW came around.