The players need to interact with the NPCs. Most often players need to ask the NPCs something or chat with them to share information. There are several types of conversation system. Each one comes with its pros and cons.
Text parsing conversation is a prompt box with a text input box for a player to input the sentence they want to say. After which, the NPC will parse the sentence and respond to the player with related information. It is similar to talking with a chat bot.
Text parsing interaction existed for a long time as old text game without graphic user interface. At that time, the computer was not fast enough so that the system would only parse certain patterns of sentence and certain keywords. It is called Ask/Tell conversation.
Ask/Tell conversation means the player will either ask the NPC something or tell the NPC something. As each NPC has its...