The very first game I played was either Battlestar Galactica on an arcade unit under the escalator at Vincent Park, East London, Asteroids on another arcade machine at the top of the escalator, or Pong on what may have been one of the very firtst consoles [if something of a one-trick pony]
My first ZX Spectrum game would have been "Thro' the Wall on the "Horizons" introductory cassette.
First game on a "proper" console was one of the Alex Kidd games on Sega Master System.
I had my first taste of PC gaming in standard 8 or 9 when I was invited to a class-mate's birthday party and got to try first Centurion and then Wing Commander. I watched the other playing the original, 16 colour Quest of Glory.