Overview

Black Crypt (1992, Raven Software / Electronic Arts) is a first-person dungeon crawler for the Amiga. It uses the Amiga’s EHB (Extra Half-Brite) display mode — 6 bitplanes, 64 colours.

The game’s data lives in a flat directory of 26 files named bcdfa–bcdfz, alongside the main executable BlackCrypt and a small configuration.dat. Each file is a different kind of data: some are HUNK executables (code overlays), some are RLE-compressed sprite banks, some are raw containers.

What this project did

The goal of this project is to fully decode every file format so the game’s art, maps, sound and text can be extracted and understood. The work is byte-level: every format is confirmed against the original files, emulator savestates, and the DOS port.

The headline results:

• All 204 monster sprites across the 13 dungeon levels extract byte-exactly.
• All 180 item icons (24×24, 6bpp, no mask) live in two RLE streams inside bcdfa.
• The three dungeon tilesets (bcdfx/bcdfy/bcdfz) are fully decoded — 84 named sub-images each, 100% byte coverage.
• bcdfa — the game’s biggest, messiest file — is a mixed container, now fully mapped: UI panels, spell effects, sound, fonts, item icons, paperdoll art, floor sprites and throwing projectiles.
• bcdfs holds all 13 dungeon maps, with a verified format walker.

How to read this site

• File inventory — the one-line summary of every file.
• Display & bitplanes — the graphics fundamentals you need first.
• File formats — one page per file format.
• Extracted assets — the actual images pulled out of the files.

A note on the raw notes

The full, exhaustive analysis lives in docs/blackcrypt/amiga/data-structure.md (≈9,600 lines). It records every format, every correction, and every dead end so the work isn’t repeated. These pages are a friendlier summary of that document — when in doubt, the raw notes are authoritative.