9193-on

Overriding a certain method may help ;)

I approached it like this:

player.removeItem('greenKey'); return 0;} if(1==1){('');

Full link: https://gist.github.com/anonymous/c78b439d8f2369e03f68

Basically, this let's you delete the green item once. After that, it makes sure that return true is never reached (because of the 1==1), so next passages through green are allowed. Kinda liked the sneaky (''); myself :P