Excelsior Phase One: Lysandia

Excelsior Phase One: Lysandia is a shareware, old school computer RPG in the tradition of the early Ultima games. The PC is a "Fixer", part of an interdimensional watch agency whose purpose is keeping the history of various worlds in line with their destinies. In this case, you are assigned to the world of Lysandia, where chaos of an unknown origin is turning them off course. Your job is to discover the origin of this problem and set them back in line.

Its official website, where the Windows shareware version may be obtained, is here. The DOS versions can be found on other websites.

Tropes used in Excelsior Phase One: Lysandia include:

Demonic Possession: It turns out all of the problems of Lysandia started when the king became possessed by a chaotic demon.
Fantasy Counterpart Culture: The two brothers who make balloons are supposed to be German or Swiss.
Get Into Jail Free: Part of the main quest.
La Résistance: The PC joins a literally underground group attempting to overthrow the king's destructive rule.
Monster Town: For one quest, you must get information in a town populated by various monsters (of the same kind you've spent the rest of the game killing. . . . A-a-a-awkwa-a-ard!)
Now Where Was I Going Again?: This game was made before journal systems became popular. If you're lucky, you might be able to figure it out based on certain items in your inventory.
Skeleton Key: Although they are called keys, functionally these work as lockpicks, and you need the lockpicking skill to use them effectively.
Translator Microbes: You need to get the Miracle Ear to talk to the inhabitants of Grethal, the Monster Town.
Unobtanium: A mineral named Eramel, used to make magical weapons and armor. Bizarrely, as far as we know it is only mined in a tower.
Wide Open Sandbox: There are many things to do beyond the main quest.