This is almost turning out to be a semi-regular trip down nostalgia lane, but I don't care!
Anyway, one of my very favourite games on the Speecy was this - Carrier Command:
You were basically in charge of a super-aircraft carrier in some far-future land with just one task: to capture more islands in an archipelago than your enemy from the opposite end. It was absolutely submersive: whole hours would disappear, as you tried to combat each island's defences, not to mention making sure your own carrier and aircraft were intact... they don't make 'em like they used to.
The clip is a recording from the audio tape that came with the game - the in-game music (being a Speccy was shite) so David Lowe was allowed some proper recording equipment. It's great. :)
After the Speccy, I upgraded to an Atari ST and thankfully Carrier Command was vastly improved, but this next game I don't think can be beaten for sheer scope: Starglider 2 - an entire solar system of planets to explore...