The Atari Program eXchange, or APX, was a mail-order program run by Atari, Inc. for the purpose of distributing software to users of the 8-bit Atari home systems. The software itself was on store shelves, as well as being available through mail-order through a quarterly catalog. The titles included application software, as well as educational titles, and of course games.
This system allowed end-users to design the programs themselves, then distribute them through Atari, which would in turn pay royalties back to the programmers. APX entries were also elligible for sizable cash prizes, as judged for quality.
Some of the titles, such as Eastern Front (1941) were later released as full Atari titles due to their quality and popularity.
At the time APX was instituted, there was a still a rise in computer popularity, but the gaming bust was only a few months ahead. Getaway! is by some regarded as the last notable title for APX, before the downturn began.
After APX was shuttered by Atari, Antic Magazine launched a replacement called Antic Software.