Mechner's games stand out in part because he seems to have done just about everything himself and, especially for the time all the parts are outstanding - the design, the artwork, the 'art direction', the animation, the gameplay. And then he went off and churned them out in 6502 assembly.
[1] http://fabiensanglard.net/anotherWorld_code_review/index.php
A lot of musicians doing game-music for the Commodore 64, for example, were popular enough in their own right that sometimes publishers would hire them knowing their names would be sufficient to guarantee sales for otherwise mediocre titles. Some of them even perform their 80's game music live today, and there's a whole scene doing remixes of the music.