18 months ago, I posted the results of 1 year's play using the
DMG's "speed factor" (p270) optional initiative system. Our goal in switching was to
(1) make player choice matter and
(2) to shake up predictable combat orders, thereby increasing thrill and tension.
We met Goal #2 but not #1. The player choice had minimal impact.
1 year ago, I posted a rough draft based off AD&D and Mike Mearl's much maligned and over-complicated Greyhawk Initiative. For the last year, it's been simplified and fixed quite a bit after brainstorming with other DMs and test play.
I've been happy to find it's met both goals and been smooth sailing!
So, first, thanks for going to the effort of reporting your experience.
I am, though, somewhat uncertain as to how to interpret your report that the DMG speed factor variant did not make player choice matter, but your modification of GI did. Both systems modify the initiative roll based on player choice, and both are probabilistic in that they favor but don't guarantee that the PCs taking 'faster' actions go first.
Conclusion: It's quick once people "know their dice" and player choice of action makes a huge difference. Players are liking the control they have versus the sheer randomness of a d20, and we've de-emphasized the notion Dexterity should have such a heavy hand given all the other game mechanics it affects. Traditional "first strike" classes like rogues with daggers have great odds of striking first. Like in the DMG system, players need to watch the battlefield and plan accordingly because despite the odds, that ogre might roll well enough to surprise you and bring that club up quicker than you were expecting. It's added something to our game without taking anything away.
Your comment at the end seems to imply that in the DMG system the swinginess of the d20 overshadows the modifiers so much that the effect is not generally obvious in the course of play, whereas using the different dice in your system more often produces an initiative order in line with the 'speed' of the chosen actions. So I ventured into the math* a bit, and, provided I did not err in my calculations, the results seem, well, mixed.
Using the DMG system, differences of 2 or less in the modifiers produce results that seem to me to be unlikely to be easily noticeable as to who gets to go first more often. In particular, for instance, in a contest of d20 vs d20+2, the d20+2 wins outright only about 57% of the time. With a difference of 3, it's about 62%, which you might notice; a difference of 4 brings it to 66%, and 5 to 70%.
In your system, a difference of one step in dice size (d4 vs. d6, d6 vs. d8, etc.) looks like it also produces results in which the distinction will not be easily noticeable (bigger die wins less than 60% of the time). But then two steps seem much more likely to be noticed (more in the range of 65% and up), and in d4 vs. d10, the d10 wins outright 75% of the time.
So both systems have dice contests in which the effect of being 'faster' would be easy to see and ones where it wouldn't, but they don't necessarily line up with the same combinations of actions. It seems like the overall effect would depend on which combinations of actions were more common at your table.
I guess my general point (if I have one) is that I'm somewhat surprised you saw a dramatic difference between the systems in the extent to which character choice mattered in determining initiative order. Any further thoughts?
* Just arithmetic**, really.
** Which
is math, of course, but 'math' always sounds to me a bit too grand*** for this kind of exercise.
*** I worry about the damndest stuff.