Based on rules.

The rules are certain and cannot be ignored or worked around.

(slang, nonstandard) Alternative form of rules are rules

(programming) A rule by which compilers are allowed to apply any optimizing transformation to a program provided that it makes no change to the observable behavior of the program.

plural of at-rule

(Internet) A type of directive in CSS (Cascading Style Sheets) that is prefixed with the at sign @.

A surname.

(informal) Australian rules football.

plural of Rule

A regulation, law, guideline. / A regulating principle. / The act of ruling; administration of law; government; empire; authority; control. / A normal condition or state of affairs.