Real men play with french voices.

Someone really loves point&click adventures! I'd extend this List with Grim Fandango, Simon the Sorcerer 1+2, Maniac Mansion, Space Quest, Quest for Glory 1-3, Zork, and Leisure Suit Larry Lafer (NOT Lovage!)

Apart from these, some shooters: Serious Sam, Quake, Doom (1,2 and Final Doom), Duke Nukem 3D, Wolfenstein 3D, Hexen, Heretic, Catacomb 3D, Blood, Unreal, Unreal Tournament

RPGs: Ultima, Might & Magic, Wizardry, The Bard's Tale, Baldur's Gate, Planetscape Torment, NetHack, The Dark Eye (both the Realms of Arcadia Trilogy and the Drakensang series), Etrian Odyssey

Others: Rune Factory, Katawa Shoujo, Sunrider, Academagica, Panzer General, Hand of Fate, Fate of the World, Dungeon Keeper, The Wonderful 101, Duck Tales, Giana Sisters

This list makes me happy.

I would also personally add Toonstruck and The Dig to your grand list of point and clink adventure games. They're not as well known, but I enjoyed them immensely.

Fire Emblem Series
Golden Sun Series
The Legend of Zelda Series

Excitebots Trick Racing: Racing has never been this fun or engaging. You're not just racing to be the first to get to the finish line, along the way there's so many things to do that'll help you get first place even if you end third. (pulling tricks, minigames, obstacles, etc). Seriously, its so much fun.

Monster Hunter series: Come on. No need to explain.

Eternal Sonata and Fragile Dreams: Art in motion.

Given that most of the easily accessible franchises will already have been mentioned, I'll go with one of my top 2 FPS' of all time. S.T.A.L.K.E.R. - Shadows of Chernobyl, and Call of Pripyat. Two of the greatest FPS' ever made.

Deus Ex- It's a perfect blend of FPS, stealth and RPG. The story, attention to detail and level design is simply incredible. Even Invisible War succeeds in those three aspects although it suffers from some poor game development decisions.

Any Legend of Zelda game- There is something special about the first time you play through a Zelda game.

Super Mario World- Perfect 2D platforming

Half-Life 2- Perfect single-player FPS and introduced physics as integral to gameplay. It's a part of gaming history.

Portal 1/2- Brilliant level design, script and puzzles.

An Unreal Tournament game- Fast-paced multiplayer fun that can't be beaten.

GTA V- Sandbox perfection

An Elder Scrolls or Fallout (Bethesda) game on PC with mods- There are few devs that can make a world as detailed as Bethesda manage, and fewer that can make one as big whilst maintaining that detail. And for everything else, there's mods.

Mass Effect 1, 2 & 3- There are few games that can make you actually feel something for NPC characters. The way your decisions carry through across the trilogy is something that just hasn't been done to the degree Bioware managed in this series.

A Mario Kart in multiplayer- Probably the best local multiplayer game you can play.

Planescape Torment- for story and writing alone

Metal Gear Solid series- There's something unique about Kojima's 4th wall breaking stealth series that just has to be experienced.

War Thunder in VR- War Thunder is an OK game. In VR, it's something special that just has to be played.

A Civilization game- The addictiveness has to be experienced!

Gone Home- A game that is pure storytelling and embraces the interactive environment. The story is uncovered as you make small discoveries and piece the bits together in your head. All story based games should have at least some of the aspects explored in this title.

A Final Fantasy from the SNES/PS1 era- jRPGs from this era were the pinnacle of the genre. Any of these titles should be tried for a taste of quality jRPGs.

METAL GEAR SOLID
GOD OF WAR
UNCHARTED

Non mainstream?

TWEWY
Tales of Symphonia (don't think this is really mainstream..?)
Golden Sun
Disgaea
Rune Factory

If you haven't od'ed on testosterone you should play Atelier. Preferably Rorona Plus, but others work too.

And ICO for being a timeless classic