Players can invest resources to improve their offensive and defensive capabilities against other players.
Allowing players to invest in their offensive and defensive capabilities introduces many strategic options into the game. The player can choose strategies that fit his skills and preferences.
Use arms race when:
- You want to create more strategic options or avoid dominant strategies in games that use the attrition pattern.
- You want to lengthen the playing time of your game.
- You want to encourage players to develop strategies and playing styles that suit their individual skills and preferences.
- Multiple players that can activate the same (or similar) attack mechanisms.
- A strength resource. A player that loses all his strength is eliminated from the game.
- An optional energy resource that is consumed by upgrades. In some cases, energy and strength are the same.
- At least one upgrade mechanisms to improve the offensive or defensive capabilities of each player.
The attack mechanisms allow players to drain or steal each other’s strength. Activating the attack and upgrade mechanisms require the player to invest energy or time. The upgrade mechanisms improve the player’s offensive or defensive capabilities or restore the player’s strength.
Arms race introduces many strategic options for players to explore, which can make the game difficult to balance. In general, it is best to implement an intransitive (rock-paper-scissors) mechanism in the upgrade options so that every strategy has a counter-strategy. For example in many medieval war games, heavy infantry beats cavalry, while cavalry beats artillery, and artillery beats infantry. In this case, the best strategy and most effective army composition is partially determined by the choices made by your opponent.
Many strategic options allow players to develop their own playing styles and strategies. For example, if a player likes a particular mechanism, she can use it more often, while if she dislikes a mechanism, she might ignore it.
Using an arms race pattern typically lengthens a game, because players always have the option to play defensively at first. This can even delay confrontation and conflict for a long time.
What resources are required to pay for upgrades is an important design decision when implementing an arms race. When strength and energy are the same, the player might over-invest and make himself vulnerable, especially if the upgrades take time to take effect. When energy is separate from strength, you need to consider carefully what the relationship between strength and energy actually is. Strength might determine the production rate of energy. This would create a strong positive, destructive feedback loop. Energy might also be converted into strength, or energy might be invested to produce strength over time. There are many options. A good way to prevent an arms race from lengthening the game too much is to make the resource to activate upgrades heavily contested, either because all players are trying to harvest the same resources or because upgrades require the player to invest strength.
An arms race doesn’t have to be symmetrical. It is possible to create an arms race with two different sides, although this would be more difficult to balance.
Many real-time strategy games implement the arms race pattern. For example, StarCraft II and Warcraft III allow the player to investigate technology to improve the fighting capabilities of his units. In these games, strength is measured as the sum of the player’s units and buildings, whereas energy is harvested by worker units and is used to upgrade and build new units.
An arms race is also often found in tower defense games, although in those games it is an asymmetrical implementation of the pattern. For example, the green and blue mechanisms in the figure below represent two different mechanisms that increase the offensive capacities of the player (blue) and the enemies (green). In most tower defense games, there are many more upgrade mechanisms: Players can upgrade towers or choose between different towers for different effects, while the enemy waves will include other types of enemies that require a different type of response by the player.