With Gothic 2 being a direct sequel to the first game, directly continuing the story with many of the exact same characters in the exact same world, and being built on the exact same game engine, they're about as similar as two games in a series can be, and so I often like to think of them as essentially one game broken into two parts. I sometimes struggle, however, to decide which of the two Gothic games I like better.
While most people in the early 2000s were raving about how great Morrowind was, I was busy playing Gothic, and my experience with those games fundamentally altered my ability to appreciate other, similar types of games because the early Gothic games were truly ahead of their time and did some really impressive things that other developers weren't doing at the time, and still aren't doing to this day. Gothic 1 and 2 are some of my favorite games of all time, being some of the most deeply satisfying and immersive action-adventure-RPGs that I've ever played.
