Thursday, June 16, 2005

SpaceCrack: Verbs

This part 5 of an ongoing game design document written as a blog. Be sure to catch up on previous posts. In the last installment, we made a quick inventory of all the pieces in the game. This time we'll dig into the part of the game that matters most to first time players, the things they can do.

Expressive Verbs: A theoretical underpinning
The immediate question that comes to mind is "what can the player do!?" If I'm remembering my game design history correctly, Chris Crawford came up with the concept of measuring the interactivity of a game by the number of "verbs" that a player can choose from. These verbs represent meaningful choices that affect the playerÂ’s traversal of the simulation/interactive story/system of psychological rewards (Feel free to insert your current favorite theoretical foundation for games)

SpaceCrack is a simple game that relies on design method I call "expressive verbs". These are simple verbs with complex environmental connotations. The result is the player can only perform a few actions, but the impact of these actions vary dramatically in effect depending on when and where you perform them.

The classic example of an expressive verb is found in Go. The player can place a single piece on the board. However, the environment within which the piece is placed provides a rich set of contextual meaning for the move. With one simple action you could win the game, lose the game or do anything in-between. In fact, the shades of meaning associated with placing a piece in Go are infinite and can take on hues of rivalry, respect, submission, deceit and more.

When designing game verbs, it is better to go with a small number of expressive verbs than to overwhelm the player with a truckload of shallow verbs. This is a fundamental requirement for creating a game that is easy to learn but difficult to master.

SpaceCrack Commands
I'm calling the verbs in SpaceCrack 'Commands' since they use up Command Points as a primary resource. Below is the complete list of Commands that can be given in the game:


  • Build a ship.
  • Move a ship to a planet.


  • Build an upgrade on a specific planet
  • Send a message to another user.
  • End the turn

All players will need to learn the required verbs in order to play a basic game. If they want to become experts, the optional verbs will help them play better. Having a hierarchy of verbs helps new users pick up the game quickly.

This is streamlined vocabulary that lets the player can place a new token, modify a token, move an existing token or do nothing. Messages add a strong social context to all these actions. Novices can learn this list quickly, but the scope of the verbs also enough room for expert player to explore a universe of game play.

Resources required to perform a Command
There are two key resources required to perform an action.

  • Crack: The first is the name sake of SpaceCrack, a miraculous nanotechnological substance known as "Crack". With this currency you buy ships and upgrades. The economics of the crack trade in the game will be discussed in a future entry.
  • Command Points: The second resource is Command Points, which I mentioned in the previous post. Most Commands takes a set number of Command Points to enact. When you perform a Command, the appropriate number of Command Points are removed from your supply. We will be adjusting the number of Command points required for each action in order to balance the game.

Time required to perform a Command
Some commands also take an integer number of turns to complete. Items that take 1 turn are enacted immediately. Once you have used all of your Command Points, you can click the "end turn" button.

Let's say you are moving a ship to another planet. This going to take you three turns. The ship will travel 1/3 of the way there and stop. That is as far as the ship can move in that turn. If it is firing its weapons, it will fire for 1/3rd of it's path and then stop. Think of the ship as being on a personal timeline that is played 1/3rd of the way through and paused.

Command and massively multiplayer games
Because turns are executed in a simultaneous fashion using a single game world clock you can have lots and lots of players and no slow down of game play. This excites me.

  • You can have a game with 2 players.
  • You can have a game with 50 players.

Cool technology that needs to be built
Commands are calculated on a central server and the results are sent back to the client for rendering.

  • Players does a command which submits the command to the central server.
  • The central server contains a copy of the game world. It simulates the results of the various orders. The server contains basic error checking to ensure that no one submits impossible commands with a hacked client.
  • A new game world state is generated.
  • The set of changes necessary to generate this new game world state is sent to each player.
  • The player sees the result of their command and may perform a new command if they have points remaining.

So far you have an idea of what the player can do, but to really make this meaningful, we need to start talking about tokens. What the heck are these planets and ships I keep talking about?

Be assured that they are more exciting than your wildest dreams. And I'm pretty sure that your dreams are wild. (I have inside information)

The next post is up! Read it now.

take care