Just as a starting note, this is just my personal feelings about house rules; you all can post whatever springs into your fevered imaginations...
When I'm thinking about tweaking the rules of Warhammer (something that happens more than is probably healthy), I usually ask myself the following questions:
- Does the new rule increase the number of special cases or rules that only apply to a single model?
- Does the new rule change game balance significantly (e.g. making a unit dramatically more or less effective for its points, or changing its overall role in the game).
- Is the new rule more complex than the current rules?
- Does the new rule require additional rolling (and time) to use/
- Does the new rule us multiplication, division, or anything more complicated than simple comparisons or additions?
- Does the rule diverge significantly from the fluff?
- Does the rule create opportunities for min/maxing or abuse, either by itself or in combination with other units or rules in the game?
- Does the rule give new capabilities to an army that are specifically not available under the current rules (e.g. widely available AP3 weapons for Nids, heavily armored vehicles for DE, close-assault specialist Tau)?
If I can answer "yes" to any of these, I will probably not pursue it any further (other than in the void between my ears).
That said, I am standing by to be struck by Rending hits the next time I post some House Rules that violate my own philosophy.
Oh, and to forestall any cries of "Why do you want to change the rules?", I say that modellers experiment with conversions, painters experiment with color schemes, gamers experiment with rules. Evil gamers
try to minimax and tweak the existing rules, Good gamers
try to think of ways to improve them. I like to think of myself as a Good Gamer. Most of the time.