OpenTomb is a cross-platform reimplementation of classic Tomb Raider 1—5 engines that were developed by now defunct Core Design. The project does not use any old Tomb Raider source code, because all attempts to retrieve sources from Eidos / Core were in vain. Instead, everything is being developed completely from scratch. However, OpenTomb uses certain legacy routines from such unfinished open-source projects as OpenRaider and VT project (found at icculus.org), plus it incorporates some code from Quake Tenebrae. OpenTomb supports not only classic Tomb Raider levels, but also custom levels built with TRLE and Dxtre3d level editors.