First, we need to break down what techniques are used in the LBBs, and for what. This allows us to fold together things that are really the same technique, compressing the rules. We've got the following basic die rolls in the LBB:
- percentile -- mainly used for random generation of details, like magic items. Anyone want to confirm or correct? This one could be dropped, since GMs are likely to come up with their own random charts.
- d20, roll 20+ -- for highly dangerous situations (combat, saving throws.) Daniel Collins has this one covered already, so we're good.
- 3d6 -- for descriptive purposes, like attributes and loyalty. The LBBs worry less about stat scores, but there are a couple things, like languages, hirelings, and loyalty adjustments that need to be taken care of.
- 2d6, roll 9+ -- for reaction rolls and turning undead.
- xd6 -- for damage and other effects, like number of undead turned. Might not need to say much about this, other than assigning damage ranges or the strength of spell effects.
- 1 (or 2, or 3) in 6 -- for chance that something goes wrong, or goes right against all odds. A short, simple passage should cover this, but the examples in the LBBs need to be tracked down and categorized, to see how best to explain it.
In addition, there are charts that need to be turned into formulas or simple procedures, like experience points needed per level, hit dice gained, spells gained. I think there are some good initial attempts we can use, keeping in mind that the short form can be out of sync with the originals in one or two places, with the understanding that individual GMs can correct this to fit their tastes.
There is also a lot of information that needs to be summarized or described in such a way that it can be improvised, or a GM can drop in an existing resource from one of the other retro-clones or another game, if more specificity is desired. This is stuff like equipment lists and spell lists.
Some rules, like naval and aerial combat, inhabitants of strongholds, or magic item generation, that need to be looked at carefully to see which parts can be fit into one of the above and which should be summarized, allowing for GM creativity.
There are miscellaneous other rules that often don't have mechanics; they're just restrictions or conditionals. These need to be gathered up, examined, and categorized.