DOSBOX: Don't change certain settings to gain an unfair advantage, cycles, for example.

This is entirely fair, but what is the "unchanged" setting for cycles? The GOG version comes with a .conf of "cycles=fixed 8000", and I suspect that's a common use case: anyone owning an original copy, however, would likely install DOSBox manually and therefore have a default .conf of "cycles=auto" (which should result in a fixed 3000). So there's already a disconnect between naive runners.

The cycle setting (others can matter though very few ever do for timing/playability) is always going to be arbitrary, whether technical or aesthetic. Most games don't throttle their speed appropriately, M&M3 included, so it often comes down to what runners find necessary and/or sufficient. My own run from a few years back set cycles to fixed 20000: according to the description, "The cycles are to keep the game at a steady but brisk pace, allowing area transitions to occur quickly." (To be clear, I'm not here to argue whether my choice is better, and have no intentions of forcing a different-cycled run into the leaderboard.) By contrast, my Swords of Xeen run set max cycles because of the continuous saving/loading, which crashes way more often without it (though at least in this case, the GOG .conf also coincides here).

Regardless of what is chosen, I recommend clearly stating settings necessary for a consistent leaderboard. The GOG standard is reasonable here, but I've used DOSBox with many games and can tell you GOG doesn't always come up with settings I consider good for even a casual experience. Their settings are no less arbitrary than others that could make the speedrun more enjoyable to play.

To be completely honest, I'm not too familiar with DOS stuff. The rule was written in the spirit of "don't run the game at 2x speed, etc". I had seen some games have separate boards for different cycles setting and so just happened to mention it specificially. There was some talk about just using the default GOG config but that's obviously no good since it doesn't even run at the correct aspect ratio out of the box!

Simply removing the explicit mention of cycles would make things quite vague so I'm open to suggestions as to how this should be rephrased.

The old Kings Quest games might be a good template for configuration. The community decided to run at max cycles for enjoyability. Now those are some cool speedruns.

In my experience running a bunch of different DOSBox games, I first decide whether the game requires a fixed or max cycle setting. A lot of older games execute as fast as a CPU lets them, sometimes leading to an unplayable mess of a program: fixed cycles solves this by suppressing the pseudo-CPU of DOSBox. On the other hand, some games require max cycles to play adequately at all: later games and a lot of FPSes fall under this category. While M&M3 seems to go as fast as possible without a fixed setting, it's also not a game that requires real-time reactions and can be played adequately under speed-maxed conditions, so it's not as cut-and-dry.

Given that we have my run (fixed 20000) and LiLbUg's run (probably fixed 3000 or 8000, would be good to get confirmation) to compare and contrast, the most notable difference between runs at differing cycles is load time and its effect on execution. A slower-cycled run is able to leverage many of the area loads by buffering inputs, but it's also a slower run in real time because of the loads themselves. A faster-cycled run, on the other hand, has far fewer opportunities to buffer, but is also faster from point to point as there is very little waiting around. I prefer the latter having watched both, though I'm obviously biased towards my own run and previous choices.

Ultimately my preference for this game is a faster run and therefore a faster cycles setting, but I'm equally inclined to hear from LiLbUg given their similar attachment. A quick check of M&M3 running at max cycles suggests it would be even faster than my fixed 20000, hence the "steady but brisk pace" rationale I apparently decided on at the time (i.e., fast but still has some pausing in which to breathe).