The early APX games were simplistic, some of them being no more than a hundred lines of BASIC. And some of them were games devloped by Atari that they didn't want to sell under the official Atari banner, like a port of the "Kangaroo" coin-op. But the quality of the user-written games improved as time went by, until they were on par with commercial releases. One game, "Caverns of Mars," was so good, that Atari moved it from the APX to their official product line, making Greg Christensen a popular example of the rags to riches nature of the computer game business.
Atari had quartely contests for the best submissions and later began giving an annual award–the Atari Star–that included $25,000. The first winner was Fernando Herrera for his educational program "My First Alphabet." He used the money to start his own game company: First Star Software.