From time immemorial – that is, the beginnings of D&D, the original RPG – RPGers have rolled dice to find out the order the PCs and NPCs act in a given encounter, Set initiative order. If you got a sucky roll, tough. Today, we have so many other rulesets and genres, but this is still the commonest method of determining order of play in RPGs. (Even though different game systems may use different terms for Initiative and initiative slots, I am going to stick with those for simplicity.) However, other games, such as FFG’s Star Wars RPG line, use PC/NPC initiative slots, or what I’ll call Open order. In these games, the GM and players still roll Initiative for each character, but each slot can be taken by any character on that side, so the order of individual PCs and NPCs may change from round to round, and it is even possible for the same character to have back to back turns.
Now, set initiative slots have some utility. First, everyone knows when their turn is, which makes it easy to keep track of who has and has not had their turn this round, as well as when many game effects (magic spells, superpowers, etc.) end. There can be confusion over this in open order games, with some players unsure if an effect ends on the same numbered PC turn they took last round, or whatever turn they are taking in the next round, even if it means the effect may not last exactly the same length of in-game time every round.* It also can shorten any debates over tactics, since there is limited discussion of changing slots, since “delaying turn” mechanics limit the opportunities for characters, PC or NPC, to “trade places.”
But those advantages are outweighed, in my opinion, by the advantages of an open order. First of all, since initiative in set order games is determined by one particular skill or characteristic, the order in any given party is usually nearly the same each encounter. If initiative is determined, as in Mutants & Masterminds, by the PC’s Agility + 1d20 + modifiers, then the PC with the highest Agility and/or most abilities that add is usually going to end up near the top of the order, while the PC with the lowest will usually be the last PC to act. Now, it can be a bummer for your PC to always be last or next to last in the round, barring an outlier roll or very slow NPCs. But being the last PC (or last of ALL the characters) for a whole encounter can have disadvantages – often for the whole group – worse than a single player always being “picked last.”
First off, what if the Buff Specialist is the slowest PC? Unless the situation is such that the party is able to prepare for the encounter, including the GM allowing some encounter-duration buffs to be applied as part of that preparation, then no buffs will happen until late in Round 1. So the party is without for almost a whole round. With open order, the Buffer can take the first PC slot, allowing one or more party members to use the benefit on their first turn.
Open order also allows more flexibility in tactics, and can make scenes more cinematic, at the same time. For example, the party of 4 PCs agrees that a strong PC will go in the last player slot in Round 1, so she gets a buff from another PC before punching their opponents’ most dangerous NPC. It would be really great if this PC could take PC slot 1 in Round 2, especially if it’s the first slot overall and have a chance of getting in two hits before this troublemaker has a second chance to hit – plus it can be described cinematically as “One-Two punches” or a “Blow to the stomach that doubles over Bad Guy and then I sweep his feet out from under him!”
Finally, an order that works great in one round might not be ideal in a later round. Suppose, in a set order game, a PC is hit badly on the last slot of the round and needs the party cleric/medic ASAP! But there are 2 PCs and an enemy NPC going before the “Doc.” Yes, the 2 PCs could delay until after Doc’s turn – changing the order for the remainder of the combat – but the NPC isn’t going to do the same, and may even be gunning for the injured PC. Now in an open order game, the players quickly decide that Doc is taking the PC1 one slot, so the injured PC is hale and hearty again by the time an enemy can act. Of course the GM can do the same and bring the biggest gun to bear on that PC at the first NPC slot. Next round, the party can decide the heavy hitters will take the early PC slots and Doc will go last to renew a buff just before it is due to end.
Open order can be house ruled for game systems that use set order, if some thought is given to how it might affect other mechanics. (Rikoshi has some wise advice in Break the Rules, Not the Game.) Recently, the GM of a Mutants & Masterminds campaign I play in, proposed using FFG Star Wars initiative system, which uses open initiative order. We’ve played two or three sessions this way and the group likes how it works. We can make use of various Advantages, like Set-up (throwing a bonus from certain checks to another PC), more efficiently, especially since more than one PC has Set-up. We can have our PCs switch off as Set-up or Attacker with just a short exchange during the encounter. There were 2 Advantages that we quickly realized would be affected. For Improved Initiative, which gives a bonus to Initiative checks, the GM was wondering if it would still be a viable Advantage, which it turned out to be. While it doesn’t help my PC personally it is helpful for the superteam as a whole, since my roll is now more likely to get us a high slot that one of us can use. The Seize the Initiative advantage (allows a character to automatically have the first slot) took a little thought on the GM’s part. He quickly ruled that when the player uses Seize, his PC must use the slot personally, in the first round it is used; on subsequent rounds in the combat, any PC is free to use it.
*Every GM I’ve played under rules it the latter, as do I