Designing Silicon Void's Combat, Part 1: Clockwork

[It's my first Gamasutra blog entry! This post originally appeared on my personal blog where previously I've written numerous articles breaking down the combat mechanics of Chrono Cross, the game which directly inspired the mechanics of my own turn-based RPG Silicon Void.]

Since the main selling point of Silicon Void (play the demo!) is the combat system, I wanted to spend some time digging into the rationale behind its mechanics. Two general principles guide my thinking about turn-based combat:

Chrono Cross itself already exemplifies #1 - in fact it was when first writing about Chrono Cross for my blog that this principle came into focus for me. #2, on the other hand, is one of the few areas where I feel Chrono Cross could stand to be improved on.

The core elements of Silicon Void's mechanics (top left & right) are unchanged from Chrono Cross (bottom), albeit with different names.

The fundamental combat mechanic of both games is building a chain of consecutive attacks, with each success increasing the chance of future attacks hitting. Time works in different ways for the player and the enemy; enemies act at predetermined intervals, whereas players are in control whenever the enemy is not.

In Chrono Cross, the exact turn behavior of each enemy is hidden from the player, and also slightly randomized in each battle. To all appearances the enemy's turn cannot be predicted, and this unpredictability is at odds with the emphasis the game puts on building combos. Additionally, enemy turns restore an apparently random amount of stamina to all players. There is still no consensus on exactly how this works, except that all players defending seems to consistently trigger an enemy turn and restore full stamina to the party.

Silicon Void's turn clock is meant to encourage medium-term planning by making the time mechanics transparent. Each action the player takes advances the clock by one tick. Enemies act when their turn indicator reaches the active position; their turn may include multiple actions but will only advance the clock by one tick. If no player or enemy can act, the clock advances until someone can.

The upcoming enemy turns are always known, so the player knows how many actions they can take before being interrupted. Additionally, stamina ("CPU" in the game's flavor) is restored at a constant rate each tick, so the player knows how much stamina a character will have a certain number of ticks in the future.

There is a definite drawback to perfect predictability of stamina recovery, which I suspect motivated the inclusion of those sudden bursts of stamina regain on enemy turns: without them, it takes much longer to recover from stamina depletion after using an Ability (analogous to Chrono Cross' "Elements"). This threatens to drag down the pace of game, particularly early on before the player has control of three characters.

I saw this as an opportunity to make stamina management more tactical, and added a new action called Charge which temporarily speeds up stamina recovery at the cost of significantly reducing defense. The Defend action, meanwhile, offers increased defense at the cost of slower stamina recovery. Using either Charge or Defend commits the character to that state for four ticks, so that there is an opportunity cost (and also to avoid tedious repetition of these actions many times in a row).

With these changes, Silicon Void's combat is "predictable enough to allow planning": the player knows exactly how many actions they can take before the enemy's turn comes. The chance of any individual attack missing, meanwhile, provides the other half - "random enough to require contingencies".

Beyond dealing damage, successful attacks add Ability Points, the resource which is spent to use Abilities. All of the basic damage-dealing abilities in the early game of Silicon Void cost 4 AP, meaning at least two attacks must succeed - the shortest combos being Weak-Strong (1 + 3) or Medium-Medium (2 + 2). A single hit or miss could make the difference between being able to deliver the finishing blow with an ability before or after the enemy's turn, such as in the scenario below:

In this case, there is a major advantage to defeating the enemy in three ticks instead of five: the active clock effect. Which will be the subject of the next post! Thanks for reading!