January 1, 2010

Game Design Decision

My first game design problem of the new year is an interesting one, and a pretty typical one. It's a good example of the stuff I think about when making games, and maybe my still-incomplete thinking on the subject will be a good example of how I try to solve these problems.

In Aurora, players have one "building" (in RTS terms), which is called a Sun and which periodically spits out troops that can be used to attack or can be sacrificed to build or upgrade a Sun. There is a small, finite number of spots on which a player can build new Suns. When a Sun is upgraded, it starts to produce more valuable troops. Suns exist at some level from 1 to 5 and produce troops of corresponding strength. The strength of a troop matters during upgrading, so if an upgrade "costs 100", you need 100 level-1 troops or 20 level-5 troops (or some other combination that adds up correctly).

So here's the question: how much should it cost to upgrade a Sun to its next level? Upgrading is a very important mechanic, since it can make a Sun up to five times more useful than it starts. I'm considering three options right now. First, all upgrades could cost some static number, like 100. Second, all upgrades could cost some number times the current level of the Sun, so building a new Sun could cost 100, upgrading it the first time could cost 200, and then 300, etc. until the maximum. Third, the cost of upgrades for all suns could increase universally, so that the first upgrade on any Sun could cost 100, then the player's next upgrade (even on a different Sun) could cost 200, etc. Meanwhile, the cost of building new Suns would stay low and constant.

My thoughts on the pros and cons of each system:

1. Static Cost
The maximum rate of upgrading accelerates, quickening the pace of the game. The player can get as much advantage out of upgrading a Sun as building a new one. Since some Suns will be better defended than others, this encourages the player to upgrade the best-defended Suns rather than expand. Players will expand slower and upgrade more, and the game space will be marked by some very valuable Suns.

2. Increasing Cost
The maximum rate of upgrading is more stable. The player can get more advantage out of building a new Sun than upgrading any. If determined to upgrade, the player is encouraged to upgrade the weakest, lowest-level Suns first before making any especially strong ones. The strategic terrain is therefore more flat, but expansion is encouraged, and so conflict may be more common.

3. Universally Increasing Cost
The maximum rate of upgrading remains totally constant. The player can get much more advantage out of building a new Sun than upgrading any. Upgrading eventually becomes so expensive that attack is more advantageous than investment, since a new Sun can be built on the remains of the enemy's. Since the location of an upgrade doesn't affect its cost, the layout of high-level Suns will be varied, like option #1.

Option 1 incentivizes a lot of quick upgrading. Option 2 incentivizes expansion and then "flat" upgrading (where upgrading is spread evenly across Suns). Option 3 incentivizes quick early upgrades (maybe, depending on starting cost) and then attacks to conquer new territory. I still don't think I understand the "feel" of these different systems.

If any one player is quicker at the start of the game than others, Option 1 ensures that that player will dominate the game before combat even starts due to the accelerating growth. I dislike games in which the outcome is decided before you even meet your opponent; it becomes a simple race or test of mouse dexterity. And yet, Option 1 offers the intriguing possibility of being able to come back from behind after some well-timed upgrading investment.

I'm bothered by the prospect of a "flat" game terrain with Option 2. I like having some targets be more appealing than others since it introduces tactics like blitzing a poorly-defended but high-level Sun. Encouraging conflict is good, but this game might not need it if I'm going for a more cerebral feel.

Option 3 introduces an interesting player decision of determining when it is more advantageous to attack an enemy than continue upgrading. And after all, interesting player decisions are what this is all about. The big negative to this system is that it slows down the pace of upgrading over time, and I worry about what that might do to the game's interest curve. But, then, maybe a stable rate of production combined with an incentive to attack would make the game more exciting in its later stages.

And there are, of course, other considerations at play. Game performance would be better with a system that encourages fewer, stronger Suns and troops, like Option 1, and that option would also allow a constant cost and therefore a simpler UI.

Right now I'm leaning towards a static cost system (Option 1).


free FONT said...
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huang said...
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