My top 3 in recent memory are:
Xcom2: I've dumped a absolutely dumb amount of hours into this game. Addictive turn based tactical combat pitting your squishy humans against sometimes utter bullshit alien odds. Randomly generate map layouts, wide variety of missions, versatile tactics and soldier classes, endlessly playable "just one more mission" feels. Robust modding community to customize everything from new character skins, refined mechanics, to total conversion mods.
Gwent: A card game based off the Witcher universe that has gone above and beyond what the simple mini game was in the 3rd game. Hundreds of cards, factions and paradigms that fit almost any play style, a rule set structure that cuts away as much 'randomness' as can possibly be done. There will always be bad card draws, but thanks to how deck composition and rules work, you can control the odds of your deck in a much more strategic way than in many other card games.
Blazblue: I like plenty of fighting games, but this one will always hold close in spite of things that might piss me off about it. Addictive, deep, snappy gameplay with a healthy sized roster of characters that all play uniquely to suit any ones needs. There is just something satisfying about honing your skill with a character(s), and going toe to toe with other people on or above your level. It is endlessly satisfying to win a match from the brink of death, or simply out playing a reading the other player. Spending hours in the training room figuring out things for the characters you play and applying them to real opponents.
SCRABBLE! I'm an avid player. My IRL Scrabble buddy moved away, though, and I've been unable to find anyone who will play me! My work colleagues decline now, after being trounced a time or two, and I've been unble to get a club started.I play online at the ISC site, which is great fun. But it doesn't replace playing a flesh-and-blood person.
really gonna expose my age and nerdity here...
Dark Age of Camelot
Words with Friends
NSA Crypto Challenge
I'm sure theres many I'm forgetting and GOOD because I'm a game junkie and I need to stay on the wagon...
ETA: DANGIT @RoboGraham: Civ III, Age of Empires, Empire Attack... make it stop...
ETA: Black & White (clearly the problem lies not with the games...)
On the casual front, CAH is the big winner. Exploding kittens is pretty fun too.
If you want to talk nerdy, I've played Magic the Gathering for years. Draft tournaments are a lot of fun and a good way to get started. All my kids play to some degree. We all play Dungeons and Dragons once a week. we also play King of Tokyo, Smash Up, Munchkin, etc.
On the video game side, I played the hell out of Burnout, Paradise City on the xbox. A sandbox driving game, what's not to love? I wish they'd make another one. On the PC side, my kids and I all played the hell out of all the Borderlands games. Playing four player co-op with them is outstanding. I built them all low end gaming rigs so it's a LAN party waiting to happen around here.