When coming up with the idea for Broken World we wanted to make a big world that players would be able to explore for a very long time. Based upon that and the fact that we don't have the time or resources to make such a large world by hand we thought it a good idea to have a procedural world with the landscape being generated based upon a tile system where each tile takes about 2 minutes to traverse in game time (it actually takes 1 minute 40 seconds, but who's counting?). So, as it's currently coded (mind you we're in the very early stages of development), here's the relative size of our world:
Each tile is 500x500 game units in size.
To walk around the world in a straight line you would traverse 2^32 tiles before reaching your starting point.
That would take approximately 429,496,730,000 seconds to walk.
Which is about 7,158,278,830 minutes;
Which is about 119,304,647 hours;
Which is about 4,971,027 days;
Which is about 710,146 weeks;
Which is about 177,537 months;
Which is about 13,610 years... maybe we should narrow our scope a bit.