Gribbly's Day Out

01 · The maps

Every level, as the game builds it

Each map below is the level as level_start ($4573) left it in memory at $8000-$BFFF, read from the emulator when the first frame of play began. The soil row under the map, which the game builds from the bottom row, is drawn beneath it.

The left 32 columns are a wall with 96 rock and crack shapes scattered at random (scatter_rocks $4BFD). The web fills rows 1 to 60 from column 32 to the right edge: five bands of 14 triangles, 16 tiles wide and 12 high (web_band_a $684D). The ground grows up from the bottom row, one column shape after another, and the floating islands are templates drawn over the web. A line of the web that a level's layout switches off is drawn with blank characters, so those triangles look open.

The map's right end has no wall. When the view starts after column 216, draw_view ($6702) reads each row on past column 255 into the next row, so the right of the screen shows the left wall one row down. Levels 0 and 1 open that way, and the dashed box at the left of their maps is the part of the first view that comes from there.

Some of each map is random. The rocks, the soil row, and the psi-grubs, which note_tile ($5ED2) puts on 6 in every 256 empty ledge cells as the scenery is drawn, differ each time a level is built. The ground, the islands, the web and the eight Gribblets are the same every time.

02 · The tables

What each level is made of

Scene list: the address of the level's list of ground columns and templates (scene_lists $E010). Ground words: the column shapes that make the ground. Templates: the records of floating scenery that follow. Web: the address of its 70 layout bytes (web_layouts $E030). Start: the map column at the left of the view as the level begins (start_cols $E050, times 8 in pixels). Colours come from the level number's low three bits (level_bg_colours $7DBF), so levels 8-15 repeat the colours of 0-7.

03 · Level 4's name

Mr Chad peers over level 4's name

Level 4 is called "Wot, no ground?", and the game draws a little face looking over a wall at each end of the name. The face is Mr Chad, and the name is his catchphrase.

The screen before level 4 begins, from the emulator, with the name on its second line, and Mr Chad as the game stores him, enlarged: two characters of the panel font at $2000, $7E and $7F, with $FE and $FF below them, as for every double-height letter. The name is at $E198.

Mr Chad is a British doodle of the Second World War and the years just after it: a face peering over a wall, often with a single curling hair like a question mark and crosses for eyes, over a complaint that begins "Wot, no": "Wot, no sugar?", "Wot, no char?". The complaints were about whatever was short under rationing, and he faded as rationing eased. He may first have been drawn by the cartoonist George Edward Chatterton in 1938, and at some point he merged with the American "Kilroy was here". Wikipedia's article on Kilroy tells his story. In the game's drawing his nose hangs over the wall, and the fingers of both hands hook over it.

The complaint fits the level. Level 4 is the one map without ground: every other level's bottom row is ground from the wall to the right-hand end, while level 4's bottom rows are open sky, down to the strip the game lays under every map. Its scene list has 14 ground words, where every other level has 35 to 65 (the table above).