Imagic really supported the Intellivision well. When I was a kid, I never really liked their games, I always went for Activisions titles. But, looking back, Imagic made some damn sweet games for the Intelly.
My favorites:
Truckin - absolutely weird. I can't explain my fascination with this game, but I love it. Pretty unique game.
Microsurgeon - two-player greatness and another neat concept.
I like the idea behind Dracula.. and it could have been fun. I think if it was 2-d, it might be better. I never really got into Safecracker either.
What's missing? Moonsweeper. I love that game, and it's a shame that it never came out for the Intellivision. I also liked Cosmic Ark for some reason, and wouldn't have minded a port for it too.
The failures? I think that both Fathom and Dragonfire could have been improved on the Intellivision, but I never cared for them much anyway.
It's funny because Imagic had quite a few games that were unique to a single system, rather than Mattel's approach to make games that could only work on all systems.