Someone commented that they thought high level fighters had it too easy in Microlite75. The commenter pointed out that a 20th level fighter could easily have a +20 to hit (+10 from level, +5 from fighter bonuses, and +5 from magic items/other bonuses) and that very few monsters had very high armor classes. This meant a very high level fighter could expect to hit almost every time. Personally, I consider this a feature, not a bug. Very high level fighters should be able to hit just about anything they aim at most of the time. This helps to them "keep up" with high level spell-casters.
However, while thinking about this comment, I realized that Microlite75 doesn't really have that many ultra-powerful monsters intended to challenge very high level characters. This is pretty much standard for 0e and 1e as campaigns simply were not expected to regularly reach such high character levels. I figured I probably should add a few more high level monsters as high level play is much more common now than it used to be.
However, I have problems with ever-increasing armor classes. Monsters and characters with an AC of -10 (about 30 with ascending AC) are unbelievable enough in my book. Going higher just to make monsters tougher for high level fighters just doesn't make much sense to me. After a while, I came up with the idea of "Natural Defense." If you naturally roll (i.e. before any modifiers) the target's Natural Defense or less on the D20 attack roll, you miss. Except for extremely powerful beings, Natural Defense is always 1. As a natural roll of 1 always misses under the rules now, there is no change to the game for the vast majority of combats.
For exceptionally powerful monsters, however, having a Natural Defense of more than one reduces the chance of high level characters hitting them without having to raise their AC to the point that no one but a high level fighter has any chance to hit them.
For example, a powerful demon might have a Natural Defense of 4 and an AC of 25. Without the Natural Defense, a very high level fighter could easily hit 95% of the time (any roll but a 1). With the higher Natural Defense, the same fighter could only hit 80% of the time. However, as you don't raise the AC to get this reduction in hit chance, less combat-oriented characters still have a chance to hit the character.
Remember, there are no fumbles in Microlite75 (fumbling on a roll of 1 would mean one fumbled 5% of the time which unrealistically high for a trained character even at 1st level). All rolling a 1 (or below Natural Defense with the rules change) means is that you missed. You don't drop you weapon, stab yourself, or accidentally cut off your friend's head.
I'm going to try this rule in actual play next weekend with some high level NPCs my players will get to temporarily play, if it works it will be added to the M75 rules. It's only a few additional words in the Combat rules:
Attack Rolls: Add attack bonus to d20 roll. A natural roll equal to or less the target’s Natural Defense (which is 1 unless otherwise stated) always misses, otherwise if the result is higher than your opponent's Armor Class (AC), it’s a hit.The bolded words above simply replace the words "of 1". A sentence about Natural Defense will be added to the rules for creating monsters and a few monsters will be added with a Natural Defense higher than 1.