As both a GM and a writer, I spend a lot of time coming up with new rules, variants, and "fixes" to the games I play. Even if you're just an occasional GM with no interest in professional design, it probably happens to you now and again, too.

Usually, it's just a matter of typing it up to get it out of my system for good - I need never look at it again. But sometimes, just sometimes, the change is actually worth adding to the game. To determine when, I put every proposed rule change, addition, or subtraction to the following simple test:

• (A) Does it add fun to the game? If so, rate the fun in Pounds of Goodness. Go to B.
• (B) Does it reduce work in the game? If so, rate the reduced work in Pounds of Goodness, and it to the pounds of fun added in A (if any). If the current total Pounds of Goodness equals zero, STOP. The change serves no function (at best).
• (C) Does it add realism to the game ("realism" being the subjective realism of the genre for genre-specific rules, or more actual realism for system-wide basic rules in a universal game). If so, multiply the Pounds of Goodness by an arbitrary value that reflects how you feel about it.
• (D) If step B added no Pounds, rate the amount of work added by the change in Pounds of Badness (if any).
• (E) If the Pounds of Goodness to Pounds of Badness ratio is at least Pretty Darn Swell in favor of Goodness, then go ahead and make that change - it's worth it! If the ratio favors Pounds of Badness, or doesn't favor Pounds of Goodness quite enough, it is not.

This formula, naturally, is almost entirely subjective! But it works . . .