Recently (today) I finished the important feature - check the field to be complitly passed. In case when you do not know the field, it is glad to trust that you can not put youself in exitless part of a chart. Thow I can use any Java classes and data structures (i.e. HashMaps or any other - my custom Lisp language interpreter hosted on Java) , I write this game only use native data structures - lists I mean :) In some cases it was uneffective, but much more authentic :)