Wow, this is an impossible question to answer.

Technically I started gaming at a very young age, but didn't really get into it until many years later. The timing of my starting gaming was about the turn of the generation from the 3rd to the 4th, but I wasn't aware of course what was going on being only like 3 or 4 years old.
Therefore, I don't know for sure what my first game was, especially with my access to my mother's and aunt's older consoles and my own 'baby-laptop' it could be an old computer game, a 2nd Gen game, a 3rd Gen game, or even a 4th Gen game on my aunt's then new SNES.
I have a few suspects though.

For a while I was only mildly interested until probably the turn to the 5th gen. Somewhere around then did I became a real gamer. However the list of games that propelled my interest is longer than the list of suspects for the very first game.
Was it a console game like Zelda: A Link to the Past, Yoshi's Island, Super Mario Kart or Super Mario 64, or was it a PC (well, Mac in my case) game like SimCity 2000, Sim Tower, Star Wars: Rebel Assault II or Dark Forces, Wolfenstein 3D, Prince of Persia or Warcraft II even?

It could potentially even be as late as Zelda: Ocarina of Time when this happened. I specifically remember the lead-up to the release of that game. It was the first game I truly was hyped for, the first game for which I truly followed it's development and anticipated it's release at the age of 10.
However, I also remember a lot of play-time before that.

I'd say either A Link to the Past or the combo of Rebel Assault II and Sim Tower are the games that made me a real gamer.

The first got me interested in the concept of consoles. I never realized there were such things as companies, story-lines in games and series before that due to young age and disinterest and was just 'playing' for the sake of playing without actually knowing the depth of it. It got me interested in all those things and opened my eyes and easily put got me aware that 'Nintendo' and 'SEGA' were different things. By extension, it made me have interest in the next generation.
The latter pair however got me addicted to actually playing things. I kept coming back to those two games. I played through Rebel Assault II countless times, to this day I can still dream every millimeter of every level. It's probably the game I've seen the end-credits for the most, and when playing Sim Tower I did such things as turn up the volume when we had dinner so I could hear downstairs if I was still making money! After that I began to want more and more.

If only I could secretly take a peek into the past to see what I was up to back then.

Oh man... I don't think I can remember THE game that got me gaming... I used to game a lot with my brothers in the late 80's and early 90's on the NES and my older brother's PC (an Amiga... 500? 600?).

The games we played a lot were War Lords, Third Reich, Zelda and Mario (amongst others). It was really a great time!!

Devil May Cry 3 was the game that really got me hooked on playing games seriously. Its gameplay is just so responsive and has an incredible amount of depths. I still don't think its gameplay has been topped.

I grew up watching my brother play the SNES though (Castlevania, Zelda, Street Fighter) and played some games from that era, but I didn't start to play games as one of my main hobbies until much later.

This was like... the very first game I started to play where I wanted to be better at it, used to play it to the point where it was just like instinct to shoot the three tanks. Great old game by Activision, if you got hit by them you could even use your crashing UFO to destroy 1 of the offending tanks.

Sonic 2 was the first game on the Megadrive which was truly Mine like as in I owned it and wanted to have more of them, I still have my copy of Sonic 2 and the Megadrive it was packed in with right now... along with owning just about every system I ever had the chance to buy and around 1.5k retail console games.

Same here. Started this game when I was 2 years old, finished it when I was 6.

Still amazed by the number of secrets in this game.

@bold, you ever play the settlers on the Amiga? that was my first experience of "PC master Race" just a game which could not be done on consoles at the time, really blew me away, that and Simon the Saurerer (spelling lol) just a very early point and click game but yeah... unheard of on consoles.

as a child i spend a lot of time watched my old brother and his friends playing SMB series, Zelda 1 and 2 , Contra, and etc2 it was a great memories actually. And someday my friend brought a SNES and played DBZ Super Butouden 1 i spend a lot of time in that game together. About a year later my old brother brought our own SNES with SMW and it happened again watching over and over my old brother beat that game, but someday i bought Zelda and i feel something different about this game and almost a year i was just playing this game alone. Then i bought CT, FF3, Lufia2, and the list goes on til now. It was Zelda Lttp can complete my early passion as a gamer and even my old brother can't a take a Snes crown for himself this time he just watching me beat this game over and over.

Had a similar-ish time with a gameboy pocket, I'm pretty sure it was my first handheld games console but because I had a drip into each arm at the joint of the elbow I couldn't close my arms together to hold it... but then along came pokemon... a game which waited for you to move then press the button... I swear I had tears in my eyes thanking gamefreak and Nintendo for Pokemon in hospital.

Pac-Man for Atari 2600. Nothing was special about it but it started a love affair that engulfed my life for over three decades. A love affair with video games by the way, not Pac-man. Pac-Man as a series is average at best. Despite me liking the 2600 version as a little child, it is widely regarded as garbage.

Yeah we had the 2600 version of pacman too... the way you could get stuck in parts of the walls if you came down on top of them was so buggy, I played it after playing on a table top arcade machine a good few times so it was very clearly a shit version of pacman first time I seen it.