Well to be frank I allways loved the Season One opening sequence (and most of all its music, which is the one I allways remember when thinking in Space 1999).
However I understand what you mean, and it is better if you decide which one to use as a basis for the game intro.
Just in case you decide to use Season One, you will notice they allways introduced footage from the episode (display "This Episode" and then a few seconds of what you are about to see). We can emulate something similar by including screenshots (I suppose animations are out of scope) of different moments of gameplay. Also we can use those moments where space is displayed to show some scrollers...
Anyway you have the experience to decide which could fit better, so... Even you can mix things from both!
For the Game over scene, someone (i don't have the Space:1999 series available) could take a still from the funeral scene, which my research reveals their was an episode with this in it.
This could be redone on the Oric, ie. i would be only too pleased to convert a pic. Not that i have gone off the music
