First Game You Ever Completed...

[GeeZa]

Sorcery on the CPC. Oh how I loved that game.

[Duck Turkin]

Atic Atac on the Spectrum.

[mrsmr2]

Head over Heels. After that I spent the summer drawing new rooms for it.

I could never get past the final, diagonal moving boss

[DTB]

Chuckie egg on the BBC clocked it twice in one session, it was insanely fast for the day by the time I died. ah the good old days

[cj2003]

Penetrator, I can still remember the fireworks at the end.

That makes two of us!!

[Devlin]

the first game I can remember completing is Head over Heels. followed by Thrust, Motos and Eliminator.
I had some serious gaming-fu when I was a wee brat.

[phattslagg]

Prince Of Persia on the ST

I think the next one after that would have been Rygar on the Lynx, then Tempest 2000 on the Jag (well, at least I made it through level 99 once, which is good enough for me).