Game Analysis#

The fastest way to understand how all of this fits together is to read a finished game — a complete, shipped program where every technique in this book appears at once, working with the others, under real constraints. This section takes well-commented disassemblies of classic titles and maps out how they’re built: the overall shape first, then the clever parts.

Each teardown opens with a block diagram of the program’s major portions — what runs when, and how the pieces connect — and then walks the structure, pointing back to the chapters where each technique was introduced. The goal isn’t to reproduce a line-by-line disassembly (those exist, and they’re linked); it’s to give you the map that makes reading one bearable.

The teardowns run roughly simplest to most elaborate — start with Pong to see the skeleton bare, then watch how much more the others hang on the same frame:

Pong (a minimal teardown) — the irreducible minimum: two paddles, a ball, four screen regions, three collision latches. The bare frame loop with nothing else, and the best thing to read right after the basics.
Combat (1977) — the launch pack-in, and one of the most-studied 2600 sources. Its structure is the frame loop this book teaches, and it’s a tour of nearly every chapter in a single 2 KB ROM.
Pitfall! (1982) — a 255-room jungle on a 4 KB cart, because the rooms aren’t stored but generated from one byte by a linear-feedback shift register. The definitive “compute the world, don’t store it” technique.
Adventure (1980) — Pitfall’s mirror image: ~30 rooms stored as a hand-authored map, with a general object engine on top. The first action-adventure, gaming’s most famous early Easter egg, and an early case of object-oriented, data-driven design.
River Raid (1982) — Pitfall’s idea turned on its side: a 16-bit shift register generates an endless scrolling river instead of a loop of rooms. The streaming-block technique, the cleanest full-cast use of the TIA’s objects, and Carol Shaw’s masterpiece.
Space Invaders (1980) — the killer app that sold the console, and the ultimate sprite-economy trick: a whole 36-alien formation conjured from just two player objects via NUSIZ copies and multiplexing. One 4 KB ROM, 112 different games.
Video Chess (1979) — the one that breaks the rule: a real look-ahead chess engine in 4 KB and 128 bytes that turns the picture off to think, holding VBLANK on and giving the whole CPU to the search. Racing the beam, inverted.
Cosmic Ark (1982) — the most famous “bug as feature” on the platform, in the actual code: a whole starfield smeared out of a single missile by strobing HMOVE and then poking HMM0 mid-comb. Four instructions. The companion read to the starfield quirk page.
Breakout (1978) — Space Invaders’ mirror image: a complete game of ball, paddle, and bricks built almost entirely from the playfield (a RAM bitmap painted by an asymmetric kernel), with the two player sprites spared for nothing but the score. The Woz prototype, brought home.

Reading other people’s kernels is not cheating — it’s the apprenticeship. The 2600 community has annotated many classic games precisely so the next generation can learn from them.