NAGI (New Adventure Game Interpreter) is a clone of Sierra's own AGI which they created and used through the 80's to produce a whole bunch of great adventure games like Space Quest, Leisure Suit Larry and Kings Quest. NAGI was created by disassembling the original AGI executable and writing equivalent C code that would run under SDL which is a free generic library for low-level access to graphics and audio. It can read both v2 and v3 game data for the PC.