Kpac is a compiler/disassembler package for the AVG32 virtual machine used in older VisualArt's titles. There is currently no public release available, since the documentation is very incomplete and the program itself somewhat unstable.

Anyone considering using a VisualArt's engine to produce dōjinshi should use RealLive via RLdev instead... but a free engine (like KAG3/吉里吉里 or Ren'Py) will probably be a better option for most people, providing advantages such as the ability to distribute a complete package of your game without negotiating a potentially extortionate commercial license for a proprietary engine.