Source Code (July 1996)
In May 2020, some LEGO Island source code was leaked alongside Beta 9.0 on 4chan.
The source code appears to be from a backup taken in July 1996, a little over a year before the final release. It contains several early design and planning documents, a compiled build with a primitive model of the island, and roughly half of the codebase at the time. Sadly, the codebase is too incomplete to make a full build of the game, however some in-house tools can be built (e.g. CONVERT and VIEWER).
Source Code
The code, despite being fairly comprehensive, is missing the OMNI folder, i.e. the entire base engine for the game. This probably constituted roughly 50% of the codebase and without it, much of the necessary code for the game is missing.
MAIN.EXE
Main article: MAIN.EXE
The build included is the earliest known version of the main game executable.
CONVERT
CONVERT.EXE is an in-house tool whose complete source code is contained in the repository. It builds to a tool that converts 3DS models exported from 3D Studio MAX to a proprietary .mod format packed into SI files and WORLD.WDB.
VIEWER
VIEWER.EXE is an in-house tool whose complete source code is contained in the repository. It builds to a tool that views the game's proprietary .mod 3D model format.