How is this different than any other commercial software library - once you have a copy, what prevents you from reselling it illegally? While HTML5 games can b

How is this different than any other commercial software library - once you have a copy, what prevents you from reselling it illegally? While HTML5 games can be easily copied wholesale somewhere else (as can Flash SWF files generally) - the code is usually minified and not terribly useful to try to do development on.