Original System: Atari 400/800
There are actually four different versions of Astro Chase between the Atari 400/800 and 5200. The original was released on tape and disk on the Atari 400/800 by First Star themselves before Parker Bros. decided to pick up the title and put it on cartridge for the 400/800 and 5200. Later First Star published their own version on cartridge for use with their Max-A-Flex arcade units which were basically Atari 600XL's put into an arcade cabinet. It's unknown if the First Star cartridge version of Astro Chase was ever sold to the public.
While the basic game between the four versions is the same, there are little graphical differences and coding changes. The most interesting of which is that the Atari 5200 version of the game was made easier! The Atari 5200 port only requires the player to shoot down 8 mines while the Atari 400/800 ports require 16! This change may have been made due to the 5200's joysticks making the game a little harder to play, but the truth is that the game is brutally hard no matter what controller is used.
The next difference is in how the text is highlighted. In the Atari 400/800 cartridge versions (both PB and FS) certain text is displayed as inverse making it appear to be highlighted. This includes the words "Presents", "Astro Chase", and "First Star Software Inc." on the copyright screens, and the level 'chase' number, number of mines, and number of saucers on the game display. These are all in regular non-inverse text on the 5200. Additionally the text "Press Select for Chase Level" and "You Saved the Earth" is displayed on a pinkish colored bar instead of the regular burgundy color. This also does not happen in the 5200 version.
Finally we have a small difference in the text displayed. The 400/800 version says "Press Select For Chase Level" while the 5200 version says "Press # For Chase Level"
The First Star cartridge and disk based versions of the game have some differences of their own. The disk version has a nice First Star Software splash screen before the game starts but is missing the credits as your astronaut is walking to the saucer. The font in the disk version is also different and uses a special non-standard font. The colors for the status bars are different as are the colors for the stars, shield depots, and energy generators (they're yellowish instead of purple) and the whole color scheme looks brighter than the PB version. Megamines are simply called Mines and the game starts on level 'chase' 8!
The rare First Star cartridge version is similar to the Atari 400/800 Parker Brothers cartridge version with a few minor differences. The text "Parker Brothers Presents" has been changed to "First Star Software Inc. Presents" and the game starts on level 'chase' 8 like the original disk based version does. This version also works on Atari XL/XE computers unlike the original Parker Brothers version. This was a necessary fix as the Max-A-Flex units used Atari 600XL computers!