Take Exalted 2e. Every body rolls a Join Battle Action. Highest person goes on tick 0. Next highest goes on next tick based on the difference, so if the highest got 5 successes and the second got 3, the next player would go on tick 2. And so on...
So, person A in tick 0 does a tick 4 action. He does his action, his marker moves to tick 4. person B goes, does a tick 5 action. He goes on tick 5. Then the tick marker goes up to 1. If anybody has his marker he goes. No one goes. Tick 2 comes... Person C is there, he activates a Charm, a tick 5 action, his marker goes to tick 7.
It's the monsters turn, three monsters. They rush in and charge, doing a slow attack that's a tick 6 action, but it does serious damage if it hits. Do action, their marker goes to tick 8.
Tick 4 next, Master NPC snickers, laughs at the heroes, does a spell and casts spell. He casts it at tick 4 speed, so his marker goes to tick 8. Person A, also his marker in tick 4, does an action that's 2 speed, and his marker goes to tick 6.
As each person acts, he does his action, then his marker moves up the chart. It's a fluid simulation of the randomness of combat. If you think on the nature of combat, this is more or less how a combat would happen.
For spells, a spell might be Charm Person, for example right. This Charm person spell might be - target person who fails his Will save is friendly towrads the caster for the next 20 ticks of combat (worded badly, but you get the jist). So, instead of durations being rounds, they'd be ticks instead.