Evolution Through Player Selection

Posted: May 15, 2011 in Game Design

I’ve already talked about using evolution in game design in a previous post. However that was mostly concerned RPG game balance. This post is about player selection of traits as a replacement for tech trees in RTS games.

RTS games usually have a wide variety units, some with few HP, some with many HP, some melee, some ranged, some quick, and some slow. However very rarely are all the units in a game available right at the start. Usually it takes time and research to gain new units, however the attributes of these units are set by the game designers and cannot be influenced the player.

Now I will propose a hypothetical game. All units in the game have the following positive attributes: HP: how much damage it can take before dieing, Attack: how much damage it can do, Range: how far it can attack, LoS: how far it can see, Speed: how quickly it can move. Additionally all units will have the following negative attribute: Support Cost: how many resources the unit consumes at regular intervals in the game. Many RTS will have multiple resources, that vary from game to game, such as food, wood, stone, metal, oil etc. For simplicity this example will use a single resource.

At the start each player can choose from a pool of units to start. These units will be similar but with slight variations. Some might have high HP and attack, but low range. That would make a good melee unit. Some might have high range and attack but low HP. that would make good support for melee units. Each player will look for attributes to fit their play style.

After the game begins players will want to make new units, which is simple enough, simply pick two units to mate to create a new unit, and all takes is a little time and a support cost paid to the new unit. No male or female for simplicity, so any units can mate. How are the attributes of the new unit decided? Through blending(which is not at all how real traits are passed on) so if two units mate, one with 50 HP and one with 60 HP we can expect the child to have 55HP.

However if we follow this method we will end up with a bunch of average mediocre units with no room for improvement, so we will add a random variation of of + or – 10, then the child could have anywhere from 45 to 65 HP. Using this players can choose units with attributes they want and breed them to improve those. Any units with lower than expected HP can either be bred to improve another attributes they might have a high number in, or sent to their death to fight against an enemy.

After several generations of player selection, specialized units will emerge with attributes selected by the player. Units bred for LoS and speed can be scouts. Units bred for range and attack can be artillery. Players can choose the attributes to fit their play style.

There is of course the matter of support cost in resources mentioned earlier. All the attributes will be used to calculate the support cost, so units with higher attributes will cost more to support. Units can be deliberately bred for low attributes so they can be cheaper to support.

Of course most RTSs will have many types of buildings, construction buildings for making units, turrets for defending a base, and many others. Ideally buildings will be selected and improve over time, but this post is long enough, so that will have to wait for another post.

PS: Anyone who knows of a game that does something similar to this, please link.

Edit: Also, if anyone has any thoughts at all on this topic, please, please leave a comment.

  1. Magnum says:

    Cool text. interesting….

  2. Fang says:

    Having not played a RTS before(unless “Dwarfs!?” counts) I can’t comment on the subject but it seems very good.

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