For me, it was Doom.
I went round my uncles house when I was about 5 and he let me have a go on it. All I can remember doing though was wandering around a few dark corridors, not shooting anything.

Pong arcade at the Purple Penny Arcade in Ilfracombe, Devon summer 1973. I was 10 years old. Queued for about an hour to get a go. My mum wasn't too pleased.

Jet Set Willy on some old amstrad i think

Cannon Fodder, war has never been so much fun.

Pong thing.

My dad made it of a kit of maplins or whatever it was called then.

Ping Pong on this:
http://en.wikipedia.org/wiki/Macintosh_128K

It was awesome - i was 6 or something.

(Don't know if it was that exact model - but it was of that series, looking like that, and it was greyscale)

Some Frogger type game is the first one I can remember. Possibly played it on a Tandy, seems around about the time I would have been in Belgium.

I think it was a game called nerf arena running around shooting foam bullets

Can't remember what it was called, but it involved a wooden hoop and a stick.

(I said I was old ).

Lt Dan.

Oooh on this topic someone may be able to help me. First game I ever played on a home computer was Jet Set Willy 1.. but when i got my Speccy 48k the next year (1987 and 7yrs old) I got given a sidescrolling shooter called 'Chronos'. I remember it being damn hard at the time but my enthusiasm pulled me through to the end of the game within a couple of days.
I have emulators for almost every platform bar the spectrum and cant find one that works effectively and I desperately want to play that game (as well as Chaos!) so If anyone has it as a rom or know a decent Speccy emu please post here!