Chrono Trigger‘s combat system is essentially the ATB system from Final Fantasy: each character has a gauge that fills up (at a rate determined by their Speed stat), and when it’s full, they can take an action, such as attacking an enemy or drinking a healing potion. When you use special “technique” attacks, however, things get a little different.
I talked recently about special attacks in Final Fantasy VI, including Cyan’s “sword techniques”. I mention this to avoid confusion: “Techniques” in CT have nothing to do with that. Instead, they take the place of spells. All Techniques require “Magic Points” to use, even the ones that clearly involve nothing more than swinging a sword around in a fancy way. Every character has their own unique set of Techniques. Some simply do more damage than a standard attack, while some have more spell-like effects, such as healing damage or putting enemies to sleep. But the special thing about them, the thing that makes Chrono Trigger combat different from standard ATB, is that many of them are affected by the geometry of the battlefield. There are basically two variants of this: those with ray effects, and those with burst effects. In either case, you target a specific enemy. Rays will effect anything in a straight line between your character and the target, while bursts affect everything within a certain distance of the target.
It’s not really a very advanced concept. Plenty of games before and since have had similar area-of-effect rules. But it combines oddly with the ATB system, particularly when you take into account two things: (1) You can’t move during combat, and (2) the enemy can. (Please understand that the player has absolutely no control over where the player characters put themselves when battle starts: even if you approach the monster from a different direction, the team will dutifully run to their assigned spots for that encounter when combat mode begins). The ultimate effect on gameplay is that you can wind up spending a little time waiting for the randomly-wandering foes to line up or cluster together in order to get the most out of your mana. Now, I complained about how Cyan’s sword techniques in FF6 forced the player to sit there and wait to use them, and considered that particular UI experiment to be a failure. But the CT system doesn’t force you to wait: it simply gives you an incentive to wait voluntarily. And I don’t often do so, but occasionally it’s worth it.
Voluntary waiting is also the effect of the other new feature of the Techniques: combinations. Specific pairs of characters — or even trios, supposedly, although I have yet to see this in action — can perform their Techniques together for synergetic effects. For example, Crono, the main character, has a “cyclone” Technique that lets him do burst damage by leaping into the middle of the enemies and swirling his sword around. Lucca, the tech girl, has a Technique that does a ray of fire damage. Do them together and Crono uses his swirling sword to deflect Lucca’s fire ray in all directions, doing a large amount of fire damage to all foes. (Weirdly, there’s another Technique where Crono does the same thing to Marle’s healing-aura Technique, in which case the deflected magic misses the monsters and hits all the PCs.) But in order to do a combo attack, all of the characters involved must be ready to act. Since everyone’s action gauge fills up at a different rate, this means sitting and waiting sometimes.