Balloon Fight

The page builds each picture from the game's own tables, the way the routine at $D293 builds the screen; an address such as $D293 is a numbered place in the console's memory, written in hexadecimal (base 16). The page uses the lists of blocks for the platforms, the clouds as 4 by 4 tiles (a tile is a square of 8 by 8 pixels), the propellers as 3 by 3, stars wherever a cell is blank, and the palette, the set of colours, for the phase's group: the colours change every four phases. The birds stand where their list puts them, in the colour their type gives, and the player waits at the left. The pictures were checked against the emulator's own screen for all sixteen layouts, and every cell below the status bar matches (work/test_phases_vs_emulator.js). A cell is one square of the screen's grid of tiles. The stars twinkle, so a star's cell counts as a match whichever of its twinkling pictures it shows. The pictures use the palette of jsnes, the emulator the kit runs.

The fixed opening ($C4AD), read the way Balloon Trip reads it ($C3C9), from left to right. Every 8 pixels of scrolling, one run reads bytes until a 0: each byte before it puts a balloon (green) or a spark (white) at the left edge, at a height the byte gives. The table of generators ($C3BF) keeps this reader for 63 runs, but the list fills only 58, and nothing sends the reader back to its start. So the last five runs, shaded, read on into the code after the list ($C527), and its bytes become six sparks and a balloon. Then the random generators take over. Press a balloon or a spark to see its byte.