Two builds, one engine
Both builds run the same simulation, proven against the disassembly and separate from how the game looks or sounds. Everything you see and hear differs, and that is chosen when the build is made rather than by a switch inside the game.
Both builds play the original forty caves, and that cave data is copied from the 1988 game. A permission request was sent to BBG Entertainment GmbH on 16th September 2026 and has not been answered. No permission has been obtained; the builds were opened on 22nd September 2026 without one.
If you hold rights in the game and want this taken down, email dan@dbhq.uk and the material is suspended while it is looked at - normally within 24 hours. Nothing here is sold, and the original disk images and executable are not offered.
The enhanced build, VIP
The same forty caves and rules, drawn from an atlas at eight times the original scale. The sprites were generated with the original 16 by 16 sprites as reference images, one animation sequence at a time so the frames agree and do not flicker. The cartoons were redrawn the same way: WIN, LOSE and TIME for each of the five 1988 worlds, 90 frames in all. The title art was generated from a written description. The sound effects are eight procedural one-shots, synthesised in the browser, and the music is a remix based on the 1987 theme by Nick Scarim, credited to him.
It plays all ten worlds, including the five the 1988 menu cannot reach, on a second page of its select screen. Those five are generated from Aleksi Sahala's reconstructions, tiles and portraits, from asahala/Rockford-Patcher: the art is derived from them and is not this project's own. His repository carries no licence. On 7th October 2026 he agreed by email to the use of his tilesets, on condition that he is credited with a link to his repository, and VIP uses them on those terms. They come down if he asks.
Generating an image does not by itself clear rights in what it was generated from, and no claim is made that it clears VIP's sprites, cartoons or hidden worlds. VIP also uses the original forty cave layouts and their quota and time tables, copied from the game. It is an independent project, not affiliated with or endorsed by the rights holders.
The faithful build
The 1988 artwork at 16 by 16, the PC speaker's eight square waves, and the original title theme. When a cave in one of the five 1988 worlds ends, it plays the original cartoon for how it ended: WIN, LOSE or TIME. This is the build the research is about and the one to judge the engine by, so any difference from the disassembly is a bug, not a choice.
It also plays the five worlds the 1988 menu cannot reach: scuba and player, which shipped in November 1987 and were dropped a year later, and music, luck and miner, which were never on the menu of any home release. Walk off either end of the select screen to find them. See the five worlds the menu cannot reach.
Those five are drawn with Aleksi Sahala's reconstructions, tiles and select-screen portraits, from asahala/Rockford-Patcher, used unchanged. They are his drawings, not the game's and not this project's. His repository carries no licence. On 7th October 2026 he agreed by email to their use here, on condition that he is credited with a link to his repository. That agreement is not a licence, and they come down if he asks.
The build contains the original artwork, title screens and music as well as the original caves, so less of it is this project's own work than in VIP. Permission to publish it has not been obtained.
What differs
| VIP | The faithful build | |
|---|---|---|
| Simulation | The same | The same |
| Caves | The same forty | The same forty |
| Worlds | All ten: the five the 1988 menu offers, and the five hidden ones | All ten: the same five, and the five hidden ones in Aleksi Sahala's art |
| Sprites | Redrawn, eight times the scale | 16 by 16, as shipped |
| Title and menu | Redrawn | As shipped |
| Cartoons | The same three, redrawn: 90 frames | The original's WIN, LOSE and TIME |
| Sound effects | Eight procedural one-shots | Eight PC speaker square waves |
| Music | A remix of the 1987 theme, new production | The 1987 theme, as the hardware played it |
| Artwork source | Generated, using the original sprites and cartoon frames as references; for the hidden worlds, Aleksi Sahala's tiles as references | The original; Aleksi Sahala's for the hidden worlds |
| Access | Public | Public |
Different artwork and music do not by themselves resolve permission for either build, which is why the notice at the top of this page applies to both. How VIP is being made.
How to play
Move with the arrow keys or W, A, S and D. To fire, hold Space or Shift and press a direction: Rockford acts on the cell on that side without moving, to pick up a treasure, push a boulder sideways or blow up dirt at arm's length. A standard gamepad works too, and on a touch screen the game shows its own pad and FIRE button.
Collect the quota, then reach the exit before the clock runs out. Falling things kill you, and so do the flying ones. When a cave ends in one of the five 1988 worlds, a cartoon shows how: WIN if you got out, TIME if the clock ran down, LOSE for any other lost life. The hidden worlds have no cartoons, so there the screen says it in words: "cave clear", "out of time" or "caught". "Game over" shows when the lives are gone. Finishing a world's four caves returns you to the world chooser, with your score and lives kept.
The full rules are on Original engine rules, with nothing to unlock first.