...Everything is described to him in text. Old games used to do this, but currently there are few text-based games. That is where Darkness Engine comes. This engine, developed in C++ by Gnm Software 2012, was created for this specific purpose, and almost every single line of the source code is commented to explain it. This is multi-platform, but we recommend you to replace some Windows-only code (those lines are commented) with their equivalents on other OSes.