Star Raiders (which came with my Atari 800.)
and
Crush, Crumble, and Chomp - one of the best turn based strategy games.  You could play as a regular Godzilla type monster, or sea monster, or even a flying monster and attack cities like San fran, Tokyo and New York.  Man, I wasted so many hours playing that game (most of the time was SPENT loading that game from cassette tape)