anyone know where I could get a game engine written in c++ similar to the game engines for Myst or Gabriel Knight?.. I want to try and get an idea on how to make one:P...

also whats this gamestyle called?....

Myst was basically written in Hypercard... =D

You can search for tutorials on text-based adventures. The basics should be the same, then you just need to add some images/animations.

This style of game is called adventure... It's sad that the genre is so dead now people don't even know what it's called anymore, hehe. Many hobbyist adventure games are built with adventure game studio http://www.adventuregamestudio.co.uk/. Someone mentioned you may want to check out text based adventure games (interaction fiction.) There are some complex engines specifically designed for writting IF, including Inform (http://www.inform-fiction.org/) and TADS (http://www.tads.org/) You could also write your own engine, but I suggest you at least look into how these engines are designed.