Video footage of that code executing: https://www.youtube.com/watch?v=3_VDM8nC9sM
I learned so much from that Atari 800 as a teenager.
Understanding the difference between COLOR and SETCOLOR (where COLOR didn't refer to a particular RGB, but referenced whatever happened to be in the specified SETCOLOR; this is presumably how the flashing alarm screen is implemented) taught me about indirection.
I wrote my own "Breakout" game in BASIC. At first I had a long IF/THEN to react to the joystick direction, and it slowed the game appreciably. I later found (after seeing an example in one of those magazines with the type-in-this-program's-source-code) that it's far more efficient to store offsets into an array, and update the paddle coordinates just from indexed lookups into the array.
I had an interest before this, and new some rudimentary basics, it's stuff like this that gave me the incentive and the means to learn much more.
IMHO, that game sold a lot of Atari computers. Was written by the guy who designed the sound chip, and it was kind of a side project that turned out great enough to showcase the computers.
The particle calculations are not well optimized. While this is seen as a bug, and there is an effort to make the game run faster, many players appreciate the slowdown in battle. There is a feel associated with that which adds a lot to the overall impression of the game. It's oddly gratifying to feel it slow down as the enemy and their shots explode...
They add a lot to the game, though the author didn't intend for it to go that way.
Funny, for that time period, there are a lot of "effects" that were resource limits, or bugs that ended up making for a better experience. Little things, like getting an extra color to work with were a very big deal.
We have come so damn far...
This did cause me to pull my old 400 out of the closet. It has this cartridge in it. Turned it on, and it plays fine. My HDTV is a bit cranky about it all though.
It came with a multi-button controller with replaceable overlays, which presaged the Atari Jaguar's controllers.
"Red 5 standing by ..."
I remember pretending be to part of the rebel alliance in that game ... many hours spent. Thanks to the designer.
Looking at the OCR of the code that provided the foundation of a tiny part of my early years is a strangely odd experience.
The source code of a childhood ...