A simple multi-player text-based adventure game engine in Java.
To run the server from the command line mvnw exec:java@server.
To run the client that will connect to the server mvnw exec:java@client -Dexec.args="XXXX", replace XXXX with your username.
- "inventory" (or "inv" for short): lists all of the artefacts currently being carried by the player
- "get": picks up a specified artefact from the current location and adds it into player's inventory
- "drop": puts down an artefact from player's inventory and places it into the current location
- "goto": moves the player to the specified location (if there is a path to that location)
- "look": prints names and descriptions of entities in the current location and lists paths to other locations
Note that in addition to these standard "built-in" commands, it is possible to customise a game with a number of additional game actions which will be introduced later. Of course, built-in commands are reserved words and therefore CANNOT be used as names for any other elements of the command language.
Game entities are a fundamental building block of any text adventure game. Entities represent a range of different "things" that exist within a game which is defined in a .dot file. The different types of entity represented in the game are as follows:
- Locations: Rooms or places within the game
- Artefacts: Physical things within the game that can be collected by the player
- Furniture: Physical things that are an integral part of a location (these CANNOT be collected by the player)
- Characters: The various creatures or people involved in game
- Players: A special kind of character that represents the user in the game
The picture below shows how an example set of game entites work:
In addition to the standard "built-in" commands (e.g. get, goto, look etc.), the game engine can also
respond to any of a number of game-specific commands (as specified in the .xml file).
Each of these actions will have the following elements:
- One or more possible trigger phrases (ANY of which can be used to initiate the action)
- One or more subject entities that are acted upon (ALL of which need to be available to perform the action)
- An optional set of consumed entities that are all removed ("eaten up") by the action
- An optional set of produced entities that are all created ("generated") by the action
- A narration that provides a human-readable explanation of what happened when the action is performed
Case Insensitivity
All commands (including entity names, locations, built in commands and action triggers) are treated as case-insensitive.
Decorated Commands
In order to support variability, the server is able to cope with additional "decorative" words being inserted into a command.
For example, the basic command chop tree with axe might be entered by the user as please chop the tree using the axe.
Both versions are equivalent and both are accepted by the command interpreter.
Word Ordering
The ordering of the words in a command does not affect the server's ability to find appropriate matching actions.
For example chop tree with axe and use axe to chop tree are equivalent and both are accepted by the command interpreter.
Partial Commands
To further support flexible natural language communication, the server is able to operate with shortened, "partial" commands.
It is convenient for the user to be able to omit some of the subjects from a command, whilst still providing enough information for the correct action to be identified.
For example, the command unlock trapdoor with key could alternatively be entered as either unlock trapdoor or unlock with key - both of which provide enough detail for an action match to be attempted.
In order to stand a chance of matching a command to an action, each incoming command MUST contain a trigger phrase and at least one subject.
Anything less than this and the intended action will probably be too vague to identify.
Extraneous Entities
When searching for an action, the server will match ALL of the subjects that are specified in the incoming command (e.g. repair door with hammer and nails).
Extraneous entities included within an incoming command (i.e. entities that are in the incoming command, but not specified in the action file) will prevent a match from being made. This is to prevent the user from attempting to perform actions with inappropriate entities
(e.g. open potion with hammer is not supposed to succeed).
Ambiguous Commands
If a particular command is ambiguous (i.e. there is more than one valid and performable action possible - given the current state of the game) then NO action should be performed and a warning message is sent back to the user
Composite Commands
Composite commands (commands involving more than one activity) are be supported.
Users are unable to use commands such as get axe and coin, get key and open door or open door and potion.
A single command can only be used to perform a single built-in command or a single game action.