Download it here
A "flexible patcher" which unlocks many game hidden features
OpenTomb is an open source remake of the Tomb Raider engine. It overhauls almost all aspects of the game engine, along with adding cross-platform support for modern operating systems and Lua scripting support.
Important links regarding the project:
Use Helix Mod: Tomb Raider 2-3-4-5 to disable.
Download and install the Tomb Raider series fullscreen border fix.
For game mods visit Core Design.