Heboris is a game developed in 2001 by Kenji Hosimoto, aka Hosiken. Many, but not all, of its behaviors bear a resemblance to Tetris The Absolute The Grand Master 2 PLUS, the latest TGM series game at that point. The game was developed using YaneuraoGameScript 2000 (YGS2K,) a scripting language and runtime environment created by Urao Yane.
Development of Heboris by Hosimoto has pretty much been in stasis since 2002. However, due to the nature of YGS2K in that it is a script language and the source code cannot be made truly inaccessible, it became the target of modifications by anonymous third parties mainly in the 2ch community. The game underwent various modifications, including implementing similar features from games such as Tetris The Grand Master 3, Tetris The Grand Master Ace, Tetris DS and DTET. The modified version is known in western communities as Heboris Unofficial Expansion, or Heboris U.E. as short. A second modified version, Heboris U.E. LITE, exists and focuses on lighter system requirements. A third modified version, Heboris U.E. MINI, also exists and features a plugin system to add or remove functionality from the game.
As the unofficial expansion development continued, it became evident that the developers were hitting the limits of YGS2K's specifications. This was one reason the LITE version was developed, but it itself was to bear the same burden as the original modification, as it was still based on the still environment. In September 2006, an individual in the 2ch forums successfully ported Heboris and Heboris U.E. into a C++ and DirectX 9-based environment, by going through the code and re-implementing the YGS2K specific calls using DirectX. A version using the SDL library also followed shortly, and the SDL version was successfully ported over to Mac OS X as well.
However, development of the C++ versions have stagnated since then. Contributors to the project still wrote code in YGS2K without migrating to C++, possibly due to the steeper learning curve and the hassle to set up a development environment in C++. The latest version of Heboris U.E. continues to be developed and provided in YGS2K.