I think you might be able to solve this with certain level of laziness, at a cost that you would sometimes need to generate more than just a single chunk. I.e.

I think you might be able to solve this with certain level of laziness, at a cost that you would sometimes need to generate more than just a single chunk. I.e. once you encounter a river, you will then generate the whole river, from source, to sink (either you have a sea, or some other already existing, but undiscovered river?) You would then need to account for 3 states of your world: a) blank canvas b) pre-generated but yet unexplored terain c) already explored terain The world in state b) would then be the one both cached and available for re-calculating :-) If I were you I would read up on pen&paper sandbox designs, i.e. Stars Without Number [1] relies on lots of random tables to generate a sector of space with different factions/tech-levels/ecosystems, combined with rules for faction interaction. This gives it a nice "I am just a small ship in a big universe" feel :) You can generate example sector [2] [1] http://www.drivethrurpg.com/product/86467/Stars-Without-Number-Free-Edition http://www.drivethrurpg.com/product/86467/Stars-Without-Numb... [2] http://swn.emichron.com/ http://swn.emichron.com/