This is the original Infocom ZIL (Zork Implementation Language) source code for Zork I: The Great Underground Empire, exactly as released by Activision under the MIT License.
The 10 ZIL source files (~12,000 lines) are presented with navigable definitions and an annotation toggle explaining the game engine and puzzle mechanics. The playable game is compiled from the original ZIL using ZILF, producing a Z-machine story file (.z3) that runs in-browser via Parchment’s JavaScript Z-machine interpreter.
What Makes v0 Special
The baseline — every other version is measured against this. If it’s different, v0 has the original behavior.
All original bugs preserved — the “Raft of Holding,” phantom combat, locked-open grate, and every other quirk from the commercial release are exactly as they were.
Infocom’s engineering on display — the ZIL source reveals how Blank, Lebling, Daniels, and Anderson built an entire world within the tight constraints of late-1970s hardware.
Z-machine architecture — runs on the same virtual machine specification Infocom designed for portability across dozens of platforms.