One type of house rule is the supplemental house rule. Supplemental house rules are created to address something that you consider “missing” from the rules system that you are using. In theory, you aren’t changing rules as much as adding new ones.
- In early D&D and AD&D, making a roll of natural 20 a critical hit that inflicts double damage (this one proved to be so universally popular that a similar was officially incorporated into later editions of D&D).
- In GURPS, making players spend a certain amount of points on non-combat skills.
- In any system in which Martial Arts is represented by a single skill, breaking it out into several skills, each emphasizing a different aspect of the martial arts (this is the province of many a splat book, including WoD, GURPS, and WitchCraft).
It’s deceptively easy to believe that a supplemental house rule won’t disrupt the game because you aren’t modifying existing rules, only adding new ones. Unfortunately, that is often not the case. Here are a few of the ways that an SHR can adversely affect your game.
Breaking out a skill
So you were flipping channels one night and came across a fun martial arts movie. The single “Martial Arts” skill in your game now seems woefully inadequate. You want a system that can emulate all the cool moves that you saw on the screen. Working diligently, you come up with a new martial arts system that divides the old skill into six separate skills.
Unfortunately, it now costs six times as much for a character to be an expert martial artist. Existing characters must now spread their points at being an expert amongst a number of skills in which they are now mediocre or even unskilled. New characters can be experts, but they now have less skill points for other abilities.
If your group thought that the single Martial Arts skill was too cheap, this may not be an issue. If, however, they balk at paying six times as much for the same character concept, you may want to change your six separate skills into special abilities that can be used by anyone with the Martial Arts skill, perhaps with modifiers based on the difficulty of the special ability.
Stifling Assumptions and Creativity
Sometimes a supplemental house rule can stifle creativity. Continuing with the martial arts example, perhaps under the official rules players felt comfortable describing the various things that a single roll represented. Now that they have six specific skills, they may feel less comfortable taking that sort of license and stick with the same six moves all the time.
Similarly, adding competencies where there were none can actually make characters less competent. Early editions of (A)D&D, for example, lacked a definite skill system. Most players assumed that their characters were proficient in basic survival skills such as making a campfire, cooking food on a spit, fishing, and gathering herbs. If your supplemental skill system includes such things, then characters without them are suddenly incompetent.
Supplemental house rules can also add complexity. A hit location system or a detailed critical hit chart may add several rolls and chart consultations to every combat round. A player used to having one or two options in combat may now have to ponder over a half dozen options before declaring her move.
If your players enjoy the new complexity, then it’s not an issue. If, however, your new rules are making portions of the session tedious, then you may want to rethink your house rule.
The Unwanted Fix
Thus far, your particular game system barely acknowedges social encounters and when it does, it’s often a single dice roll. You decide to fix this by creating house rules that turns every social encounter into a series of skill checks with variable modifiers. Problem solved, right?
Ask the roleplayer in your group. You probably just took the one aspect of the game that he really enjoyed and turned into a combat encounter with a different coat of paint. He will absolutely loathe the new house rules. Conversely, players that would rather dice their way through scenes (e.g. We need to get through that door? Okay, I walk up to the guard and try to bluff my way past him. What do I need to roll?) will probably welcome the additional rules if they add flavor.
While supplemental house rules may seem like harmless additions, there are factors to consider that may cause you to rethink implementing the house rule. Just because it doesn’t significantly affect existing rules doesn’t mean it won’t have an adverse impact at the table.
What about you? Have you implemented supplemental house rules? If so, what challenges did you face? Did you end up keeping the house rule, revert to the original rules, or come up with a different house rule?