A lot of people who join my Kodia servers tell me how I'm "Epic" at the sort of thing, so I guess I'll lend a few tips over.
-Co-op is all ways nice, but don't make it to where "ever one is happy" because then one guy does all the work while others follow.
-Add more depth to the basic, cut a tree. sell it. 5 gold. buy a sword.
EX: In Kodia, new beginnings you would chop down the type of tree, lets say the Yew, and once after that you will have to find the single "Yew Cabin" to which you can carve your single log in to 3 Yew planks. But also to add more depth to that, a Nice way to get the Exp For a Log you would have to make a choice to hand it over to the saw mill (with only Exp in return), or make it to planks and sell with no EXP given.
-Try not to use what I call (Land Walls). Which is basically using walls to surround your RPG, try to make it so you can go any where, as long as your skills are allowing you to.
-Get this strait, Medieval means knights, and kings, and wars between lords and such. and Fantasy is Orcs, and some trolls, and some magic crap. Make sure you know what your REALLY out to model your RPG as.
-I'll add more tomorrow, for now I GTG to bed.