We are using OSRIC as a base, which uses a D6 initiative group system. The number on your die portrays when the other side takes their turn (allowing the high roll to win). Contrast this with first edition where the roll determines who "possesses the initiative for the round."
The disconnect occurs in the elimination of abstraction that occurs in later editions. For example, in second edition, initiative is rolled on a d10 which specifically determines what segment of the round your action occurs, modified by weapon speed, casting speed, and your dexterity modifier. OSRIC works from this definition also - the number show on your opponent's die is literally the segment you act on.
In first edition, it is assumed that the roll does not represent the actual time measurement that the action takes place, but rather an assumption on who possesses a momentary advantage during the chaos of the round. Actions are then assumed to be modified from this momentary advantage -- not in a quantitative sense. One example that shows this can be seen in that spell-casting disregards initiative when compared to other spells being cast - initiative is only referenced when the spells have identical casting times. Otherwise the spell with the shorter casting time goes first regardless of the dice roll.
The problem occurs, in that in the old system actions are announced before initiative and then remain unchanged. Since it isn't representative of time, arguments based around the idea that 'if I lose initiative I can change my action because it happens later' disappear. Because the action doesn't happen later -- it's happening currently, we just resolve the action in a certain order and apply effects based on an abstraction of 'advantage'.
However, when the result is tied into an actual time-key, several problems result.
- You have this kludge, where you're rolling for the other side to keep "High roll wins".
- Players legitimately want to know why they can't change their actions if they lose initiative.
- Winning initiative becomes less of an advantage.
- It results in more calculations and math.
- It must be short, simple, and easy to remember
- It must cover the most common cases
- It must make enough sense that it doesn't create Fridge Logic moments
Initiative is not representative of when things occur during a round. It is an abstract that determines during the chaos of a round which side achieves the results they wish first.
- The DM decides monster actions and keeps them secret
- Players declare their actions. If a spell is not explicitly declared by either party at this point, the opportunity to cast is lost.
- Pre-initiative actions are resolved.
- Movement only
- Missile Fire
- The winning side resolves their actions. Spells may be canceled, but new actions cannot be taken.
- The losing side resolve their actions