Dragon Warrior for the NES. I had a few other games (Mario, etc.) before that but it was my first RPG, and I was absolutely hooked.

OG Simcity—although Wing Commander and X-Wing are close runners-up.

LodeRunner! Yes! Proving yet again there's a cohort of us wired up the same way. I'd love to find a version that runs on modern devices. 

We had an Atari 2600 with some frustrating games (Q-bert, Frogger, Tanks, Pong, etc), and then Nintendo and a bunch of games. But i really thought Sim Ant on a laptop felt like the future. My first non-console game. 

Galaxian, arcade cabinet version. Pong and Space Invaders were out before Galaxian, but the gray/black and white was boring.  Color!

Final Fantasy for the NES.  Felt like a nearly endless world with infinite secrets to discover.

Excitebike - similar reasons. 

co-signing Lode Runner! 

But also Pac-Man on the Atari 5200, and later Dragon Warrior & Tetris on the NES. 

Oh, also Hero's Quest/Quest for Glory games on the PC (So You Want To Be A Hero, Trial by Fire, Wages of War). 

For me, it was Star Control 2, released for MS-DOS in 1992. It had a vast universe to explore; mysteries to solve; resource gathering; customizable ship; customizable fleet; encounters with aliens that could be friendly, hostile, or in between; 2-player melee; great writing and music. It managed to be silly and serious at the same time. I still have the big fold-out star map that came in the box.

Total Annihilation was the only game I was really hooked on, with maybe the original (or very early)  Warcraft being a close second (yes me'lord). However my wife made it clear long ago that gaming was never going to be a hobby of mine if she was going to be my wife, so that was the end of that. I did play Minecraft or Lego Star Wars with my kids when they were little but now that they are out of the house and I don't game at all (again).

The Logical Journey of the Zoombinis! It was a Brøderbund game in the 90s that was a visual series of logic puzzles. Great art, great voice acting, and minimal time pressure; it’s still pretty much my ideal casual puzzle game.

Prince of Persia, then Prince of Persia 2. Honorable mention to Warcraft 2.

I don't identify as a gamer because I've never owned any kind of video game system, only computers. But my origin game is Dig Dug on Apple IIe! And it tracks because I am obsessed with earth work and am often digging holes for plants and just plain pleasure because who doesn't like moving soil around with a stick and discovering slash annihilating grubbers in their patch!! 🐛

Zork I was the first game that absolutely hooked me.  Galaga in the coin-op world, and Ultima III (on the C-64) in the RPG world.

Pick Axe Pete! on the Magnavox Odyssey² — a simplistic take on Donkey Kong. There were other touch points along the way that inspired going into design for screens (Zaxxon on Colecovision and Super Mario Bros on NES), but it all started on that Magnavox.

For me it was Pac Man at my local pizza parlor.   But what really toom me over the edge was X-Com : UFO Defence in 1994.  

Looks similar to Lode Runner but mine was Jumpman on C-64. Such good times. 

Can you be a "life-long gamer" if you only ever enjoyed two games? Super Mario Bros. is the only game I've ever finished. Dr. Mario is the only game I play. The NES controllers for the Switch are A+++. My "life-long" will last only as long as my thumbs.

For me it was Zelda and Super Mario on the NES during summer vacation at my cousin‘s home. 

absolutely Lode Runner (on the Apple IIc).  NHL '93 on the Genesis. 

Space Invaders on the Atari console, in my family's house in Midlothian, Virginia. My parents had converted the garage to a playroom for me and my brother. Sitting on the couch in front of the TV, I somehow, amazingly, figured out what I assume was an intentional Easter egg. You could get double shots if you followed some random pattern with the power switch and the reset button. Amazingly, over at his house, my friend, Jamie, figured it out the same day. That was 1978. We barely had phones! Last night, I eked out a win in EAFC over our 15-year-old son, who spends all his time talking to his friends whilst playing video games in our basement. Apples and trees.

Rogue on the IBM PC Jr. Hooked for life. ASCII monsters live in my brain. I've only ever made it all the way down and all the way up twice in 40 years.

Also not a gamer, but Chuckie Egg on the ZX Spectrum (loaded via cassette tape) was my foundational childhood game  

Also Manic Miner, Jet set Willy, Penetrator, Lunar Jetman, and Elite. 

I’ve not played a game with any regularity since those ones in the 80s, but I remember them so fondly. 

Tetris on the Game Boy. Personally, I feel it's the purest example of the form.

I think the first game that really stood out to me for its story was StarCraft. I was floored by the big plot twists. The exceptional gameplay helped, of course.

Hunt the Wumpus on a Commodore PET. Thrilling adventure world to explore? Explode-y head, never look back.

Ocarina of Time ignited my imagination as a kid and holds a special place in my heart to this day. I'm very curious to see how the magic will translate to the remastered edition due this November.

I'm not a lifelong gamer but Elite on the BBC micro.

My teen years were spent dropping quarters into arcade games like Tempest & Galaga. But the first non-arcade video game I played at was Choplifter, on a friend's Apple ][  in 7th grade, c.1982. 

By the time I was a college freshman and had my own Mac SE there was a lot of procrastination with Lode Runner.

But the real "origin story" came in my junior year (1993), in a basement lab of the UCLA hospital, where my best friend introduced me to their networked PCs and we played Doom - together - at the same time! 

Also Lode Runner!

Dragon Warrior, Final Fantasy, Chrysalis (where my Chrysalis-heads at?), and SimCity 2000.