A quick one today but I wanted to talk about being intentional with your terminology in rules writing.

I think game writing can benefit tremendously from being very clear about when a given rule or situation is a choice versus being a requirement.

Let's say your game has a saving throw in it: When a figure takes a hit, they get to roll a die to survive. Simple right?

What is the difference between "When taking a hit, the figure must make a saving throw" and "When taking a hit, the figure may make a saving throw" ?

In the first example the saving throw is mandatory. If you get hit, you roll to save. In the second example however it is not. If I "may" do something, it stands to reason I "may not" as well. Why would I not want to make a saving throw? While counter-intuitive I might want to be rid of that particular figure because they happen to be in the way of another unit or because that will put the unit out of charge range or any of a thousand other reasons. 

Are those reasons things you want to entertain in your game? Perhaps not, in which case the saving throw should probably say "must". But maybe you are making a game that is more abstract or competitive and the decision is in fact something that a player should be able to manipulate for success. If so, they "may" make the save.

For another example lets consider a unit moving into base contact with an enemy. 

A: "If any units are in base contact they will fight a round of close combat". 

B: "Units in base contact may fight a round of close combat". 

Again the meaning is clear: A has to fight while B can fight if they like. In this case there may again be reasons why they do not want to such as them just trying to slow down the enemy or adding bodies so another unit can attack and get a bonus for outnumbering. 

In B the range of tactical possibilities is greater. So is the range of strange situations that can occur. A resolves immediately (potentially) but it also means some interactions can't take place. 

Take a moment to look through your rules and see exactly what you are permitting a player to do. Does any of the rules produce a strange result if the player decides not to do something? If so, you may have to account for that or at least mention the possibility. 

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