I have too many to pick one, so I'll just list some of them out.
- Discovering the secret maze game built into the Sega Master System's firmware.
- Blowing air on NES cartridges.
- Going to Toys "R" Us, in hope that there were "slips" left for the game I wanted. Grabbing said slip and checking out using Geoffrey Bucks. Handing the slip with the stapled receipt to the person sitting in the magical room within the store to get the physical copy of the game. Man that process was the best as a child.
- Up, up, down, down, left, right, ... you probably know the rest.
- Always wondering why Super Mario Bros. 2 looked so different than the other Mario games.
- Spending weeks (probably months?) making my way to Mike Tyson, then getting destroyed within minutes.
- Seeing the movie The Wizard where they debuted Super Mario Bros. 3 and the warp flute.
- Saving up for a Game Genie so that I could do super weird stuff with my NES games.
- Riding my bike to the local comic book shop several times a week to place my quarter on the Street Fighter II machine.
- The Sega Genesis start up sound.
- Buying Mortal Kombat for the Sega Genesis and putting in the "blood code" as soon as I got home. I'm 99% sure my parents didn't know the game had this when they allowed me to buy it.
- Turning on our household Macintosh computer, turning off the lights, putting headphones on, and getting super lost in the game Myst.
- Turning on the N64 for the first time, playing Mario 64, and thinking I was in the future.
- Proximity mines and 4-player split-screen battles in Golden Eye.
Ok that's all for now! I have so many more video game memories (especially for computer games and arcades). It's been such a big part of my life and I really want my kids to enjoy a similar experience.