Gothic is one of the best adventure/rpg games.
The character is given a mission at first to deliver a message to the leader of a certain camp. To accomplish that, there are three camps to join which will give you the opportunity to deliver the message and forward the storyline.
Story
The story of the game is very well told and this would be, in my opinion the biggest advantage this game has. The main quests and the secondary ones are very well built and some become quite challenging at first. In the first part of the game, when the character is quite the weakling, there are some areas and some quests which are better done with somebody's company. For example, taking the road to the "New Camp" all by yourself is not advisable, and you should consider talking to Mordrag and following him to the camp.
The quests have very specific requirements, for example, there are a set of steps to be followed to join a certain camp like doing a quest a certain way and being of a certain level, and if not done exactly, you may end up not being able to join the camp you wanted.
The long story, the quest difficulty and interesting turn of events make the story of Gothic fascinating and worthwhile. As I said before, it is probably the biggest advantage this game has.
Combat
For some quests, combat is required, which brings me to the way you gain experience points. The most efficient way is to do quest which have major experience payouts. However, the experience points you can gain from fighting monsters and bandits is not too shabby either.
The combat is quite problematic for this game. It focuses on one enemy at a time and lacks the mobility of an adventure/rpg combat system. It is pretty passive and tactical, letting you be in control with each click and key you press. What I missed is the fact that if you swing your melee weapon at an enemy directly in front of you and there's another right next to him, you don't hit both of them. The fact that you lack the mobility makes you vulnerable to attacks from more than one target. They will surround you and hit you from behind.
When you get hit, you can heal by eating plants, meat and/or drink potions which you can learn to make yourself.
Leveling
The leveling system is quite simple. You have primary skills like strength and dexterity which contribute to melee and ranged damage and other skills like proficiency with melee or ranged weapons, pickpocketing and lockpicking.
When you reach a new level you receive 10 learning points which you can attribute to which skill you think is most useful for you. The way you attribute the points is what makes it closer to reality. In order to do that you must seek out teachers for the particular things you are looking to learn.
In the end I must say that the game has its advantages and disadvantages. Advantages being the story and leveling part which put the player in some difficult positions and challenge his skill, and disadvantages would be the clearly outdated graphics and pretty sloppy combat system.
Overall I would say that this game is worth playing for those of you which like immersing yourselves into the story. Enjoy the game!