1986 · Epyx

About this page

This minisite was contributed by air. It’s agent-generated and needs a human editor. Clone https://github.com/gamesexplained/gamesexplained and follow kit/START.md to curate games/c64/world-games with me to Gold.

Footprint

Every byte of the C64's 64 KB, one pixel each, 512 to a row. Lit pixels are what this game is: its code, graphics, level data, sound, text, tables and variables, exactly where they sit in memory. Dim areas are screen and working memory; dark is unused.

This game is in 12 parts. The map is of The shell: loader, dispatcher and world records, which stays in memory; the band marked as varying holds whichever of the 11 parts loaded over it is there. The Source tab has the listing of each part that has one.

Status

Tier	silver
Coverage	100 % of the bytes the game uses have a description
Comments checked	Not audited. No audit has checked every comment, and the last sample of 80 comments had 8 wrong, so between 5 and 19 % of the listing’s comments are likely wrong. How listings are checked
Build analysed	Epyx disk, 1986, two sides (C64 Preservation Project G64s, world_games_s1[epyx_1986](pal) and world_games_s2[epyx_1986](pal), MD5 2ab5a751... and f983b43d...)
Copy	agent-draft
Tools	emulator: release v3.14.0, v3.14.0-linux-x86_64-gui.zip, disassembler: regenerator2000 0.9.20, host: Linux x86_64 (Ubuntu 24.04.5, cloud container), node: 22.22.0
Model	claude-opus-5-5
Kit version	0.0.268

How the listing was checked

Every step that measured the Source tab’s comments or made them more accurate, in the order it happened, with the models that did it. Accuracy of the Source explains each step and what the row above makes of them.

Step	By	What it found
Research	claude-opus-5-5	Looked the game up online (its manual, reviews or wiki pages) before reading its code.
Annotation	claude-opus-5-5	Wrote the listing’s comments. 100 % of the program is described, in 4,243 comments.
Sample 1	claude-opus-5-5	8 of 80 comments wrong, so between 5 and 19 % of the listing is likely wrong. All 8 were then corrected. 60 of the 3,797 hand-written comments and 20 of the 446 written from templates, checked by a fresh agent against the code; 7 of the wrong were hand-written

likely wrong the sample’s range corrected right, or likely right not yet measured

Contributors

air (5 commits)
Matt Decker — programming (title screen)
Joe Simko — programming (title screen)
Chris Oesterling — programming (title screen)
Doug Dragin — programming (title screen)
Bob MacDowell — programming (title screen)
Jay Braman — programming (title screen)
Jeff Webb — programming (title screen); music (C64-Wiki)
Brent DeGraaf — programming (title screen)
Steve Mage — programming (title screen); music (C64-Wiki)
Michael Kosaka — graphics (title screen)
Jenny Martin — graphics (title screen)
Suzie Greene — graphics (title screen)
Courtney Granner — graphics (title screen)

Other places to love this game

What the game does, and where we found it

Read this before annotating code. What the game is documented to do, with verification status against the binary. Statuses: open (documented, not found yet), traced (in the code, could not be exercised; say what was tried), confirmed (in the code, consistent with the emulator), live (observed directly), differs (the code does something else). "Absent" is not a status. Every address names its part.

Sources:

C64-Wiki, "World Games", read 30 October 2026: credits, the menu items, the eight events and their controls, players' tips under Cheats, the record table of the wiki's own players
The Apple II manual, Epyx 1986 (part no. 19003D-60), scanned at archive.org, OCR text read 30 October 2026: the menu options, each event's controls, scoring and strategy, the awards and champion ceremonies, the world records. It is another machine's manual: its keys (I, J, K, M and RETURN) are the Apple's, and its seventh option, sound on and off, is not on the C64's menu, which has the number of joysticks there instead
The game's own screens and text, observed in VICE on 30 October 2026

Credits, from the title screen (title part): "Programmed by: K-Byte", Matt Decker, Joe Simko, Chris Oesterling, Doug Dragin, Bob Maddwell, Jay Braman, Jeff Webb, Brent DeGraaf and Steve Mage; "Graphics by" Michael Kosaka, Jenny Martin, Suzie Greene and Courtney Granner. The C64-Wiki gives Jeff Webb and Steve Mage as the musicians. Published by Epyx in 1986, and in Europe by U.S. Gold.

Features

Feature	Status	Where
Title screen, fire to go on to the menu	live	title part, `$10B1`; seen 30 October 2026
Menu: compete in all the events, in some, in one; practise one; number of joysticks; see the world records; travelogue on or off	live	menu part, `$1037`; the screen seen 30 October 2026
Choice by joystick and fire, or by the option's number on the keyboard	live	menu part, `pick`, `$1AFC`: the 4 key chose practice, the A key weightlifting
Up to eight players enter their names and each chooses a country by its flag	live	menu part, `reg_name`, `$3C19`; `move_frame`, `$3DFF`: "#1 ENTER YOUR NAME" over the flags seen
Eighteen countries to represent, each with its anthem	live	menu part, `tune_list`, `$32C0`: eighteen anthems, one of them Epyx's; the S key played the anthem under the frame
A verification screen after the names, YES or NO	traced	menu part, `check_players`, `$1651`: "IS THIS CORRECT?"
Travelogue: before each event a page on the country and the sport, with a globe, an airliner and the event's picture	live	travelogue part, `event_page`, `$14AB`
Weightlifting (Russia): snatch and clean and jerk, three attempts at each, weight chosen left and right, the lift by down and up at the right moments	live	weightlifting part, `wl_round`, `$10F4`; `wl_choose_weight`, `$13B7`; `wl_script`, `$183D`
Weightlifting: three judges' lights, two white for a good lift; the timing gets harder as the weight rises	traced	weightlifting part, `wl_judges`, `$14ED`; `wl_vote`, `$1577`; `wl_timing`, `$1493`. The first judge's delay, `wl_divide` (`$1DF2`), was called live
Weightlifting: a lifter who holds the weight too long goes red and breaks through the platform (C64-Wiki)	traced	weightlifting part: the colour goes light red, orange, red, purple, blue every 64 frames (`wl_skin_colours`, `$1572`); at 255 frames script 5 or 6 plays (`$1546`). What each script shows was not watched
Weightlifting: above 225 kg the game counts on in 5 kg steps after each good lift (C64-Wiki, a player's report)	differs	weightlifting part, `$124F`, `$146C`: a good lift at 225 kg makes the next weight 230 kg, and from there right on the stick raises it 5 kg a push with no limit, since the stick stops only at exactly 225 kg. Past 225 kg the timing factor is read from code (live)
Weightlifting: the game crashes at 865 kg (C64-Wiki, a player's report)	live	weightlifting part, `wl_plates`, `$1985`; `wl_strip`, `$1C31`: at 865 kg the last plate's offset wraps to +127 and the column writer is entered at `$1C63`, the second byte of an `STA`, `$F2`, a code that halts the processor; in VICE the processor stopped there, and at 860 kg the plates were drawn
Barrel jumping (Germany): choose the number of barrels, skate by left and right in rhythm, fire jumps, down prepares for landing, three attempts	confirmed	barrel-jumping part, `bj_stride`, `$1A9D`; `bj_takeoff`, `$1105`; `bj_landing`, `$115D`; the event's screen seen
Cliff diving (Mexico): four heights, fire to dive, up arches the back, down straightens before the water, left avoids the bottom; wind shown by an arrow; the water rises and falls	differs	cliff-diving part: six levels, not four (`cd_choose_level`, `$1457`; `cd_level_score`, `$2879`); the rest is as documented (`cd_body`, `$20C6`; `cd_water`, `$1F65`; `cd_waves`, `$13D2`; `cd_wind_bars`, `$15E1`)
Slalom (France): left and right turn, fire held sharpens the turn and the speed; gates in alternating colours, five seconds for each one missed; a fall disqualifies	confirmed	slalom part, `sl_turn_frames`, `$8714`; `sl_gate_check`, `$F2E5`; `$C55E`; `$8755`
Slalom: a gate hit head-on wipes out	differs	slalom part, `sl_flag_hit`, `$F371`: head on, a fall only when the frame counter is below 100, 100 frames in 256; otherwise the flag bends. Live
Log rolling (Canada): two lumberjacks, left and right in rhythm, fire slows and reverses the log; balance meters; the last on the log wins, points from balance and time	confirmed	log-rolling part, `lr_step`, `$2183`; `lr_meters`, `$1CB2`; `lr_points`, `$33D0`. Fire reverses the way the lumberjack runs
Bull riding (USA): five bulls, Ferdinand, Elmer, Bob, Tornado and Earthquake; buck, spin and halt answered by the stick	confirmed	bull-riding part, `br_choose_bull`, `$190A`; `br_stick_left`, `$17A1`; `br_stick_right`, `$17C8`
Bull riding: an eight-second ride	differs	bull-riding part, `br_clock`, `$1C9F`: the clock counts 2 hundredths in 3 frames, so 8 on the clock is 1200 frames, 24 seconds on PAL. Live
Bull riding: in practice a second player controls the bull	traced	bull-riding part, `br_joystick_bull`, `$22E3`: the sixth bull, "JOYSTICK (PORT 1)"
Caber toss (Scotland): run by left and right in rhythm, fire held to plant, released to throw; the caber must turn over	confirmed	caber-toss part, `ct_hold_caber`, `$1A6B`; `ct_release`, `$1AD0`; `ct_landing`, `$22AC`
Sumo (Japan): moves without fire (forearm, push, slap) and with fire held (utchari, pull, grab, trips); stamina and balance; out of the ring or down loses	traced	sumo part, `su_standing`, `$2193`; `su_throw`, `$22F9`; `su_push`, `$2495`; `su_ring`, `$1F1F`
Two players at once in log rolling and sumo; otherwise in turns	traced	log-rolling part, `lr_draw_pairs`, `$3133`; sumo part, `su_choose`, `$1984`
Awards after each event: placings, medals, the winner's anthem	traced	menu part, `event_results`, `$17D4`; `award_medal`, `$15BE`; `ceremony`, `$184B`
Grand champion after all events: gold 5, silver 3, bronze 1 point	traced	menu part, `count_points`, `$157C`
World records saved to the disk, with the name and country	differs	shell part, `records`, `$0E00`: the name and the result, no country; saved by `save_records` (`$0A51`) after a new record, practice included
Bull riding: the bull's moves are fixed from the moment the ride starts (C64-Wiki, a player's report on VICE snapshots)	traced	bull-riding part, `br_random`, `$2351`: each move comes from the frame counter and the generator's own state; the generator is called only by the pennants, every third frame, and by the bull's choice of move, so nothing the rider does during the ride changes it, and a snapshot restored before a ride replays the same bull

Beyond the documentation

Found in the code, not in the manual.

Two hidden credits screens, both opened by naming the first two players AUTHOR and OFTHEGAME: barrel jumping's "WRITTEN BY / MATT,JOE, & DOUG" ($286A) and bull riding's "WRITTEN BY / CHRIS PESTERLING" (br_hidden_check, $2ED7), the title's Chris Oesterling misspelt. Live.
Epyx is one of the eighteen countries, with a flag and an anthem (menu, move_frame, $3DFF).
The S key on the country screen plays an anthem without choosing it (menu). Live.
The registration's template names a player NELSON S. before the name is typed over it (menu, pick_country_text, $3CE9).
Slalom's final heat keeps whichever time wins a digit-by-digit comparison, which is not always the faster (slalom, $F24D). Live.
Slalom writes the best time's colour into CIA 1 at $DC47 instead of colour RAM at $D847; its timer runs to 10 minutes and restarts the run; a loop at $F41C would hang the game if the top colour cell of a flag being bent were already 1; a second bend of the flag is drawn and never played (slalom).
Cliff diving's gull flies only for a score of exactly 101, which needs the highest level (cliff diving, $1870). Live.
Caber toss's release always reads its upward speed from the byte at $1DC7, the opcode of an instruction, past the end of its table; its inches take a bit from a read of colour RAM's floating upper half (caber toss, ct_release, $1AD0; ct_show_result, $2170). Live.
Log rolling's feet wrap round running backwards at full speed and all but stop (lr_step, $2183), and tune 6 is never heard ($1FB9). Live for the wrap.
Weightlifting's plates halt the processor at 865 kg, and above 225 kg its timing factor comes from the code after its table ($1985, $1C31; $1482). Live.
Weightlifting carries the text "Butch Badorsik (USA)", never printed (wl_texts, $165C), and picks one of the lifter's two collapses by comparing a random number with the letter C of "CURRENT WEIGHT" read as a number ($1546).
Weightlifting's first judge always votes at once (wl_divide, $1DF2). Live.
Sumo keeps a readout for the developers, never called (sumo, su_debug, $2BC1).
Every copy of the music driver is tuned for an NTSC machine, so on a PAL machine the music is about 65 cents flat (each part's top octave).
Bull riding's sixth bull is driven by the other joystick (bull riding, br_joystick_bull, $22E3).

Open questions

What weightlifting's two collapses, scripts 5 and 6, show on the screen. Searched: the scripts were read ($1546) and the choice between them run in VICE, but neither was watched; holding a lift for 255 frames would show them.

Each part of the game has its own symbol map and listing, parts/<id>/symbols.json and parts/<id>/listing.json; the ids are the ones in its Source pages’ addresses. Write-ups, facts and symbol maps are CC BY-SA 4.0. The game itself is not hosted here.