i always (well sorta) wanted to see a mmo based off the riverworld books, maintaining a fair amount of closeness to the books. of course youd be able to make any weapon you want, provided you have the materials needed, and rather than foolish levels to determine what you can and cannot do, some kind of system (similar to the one in sapiens i guess) to make it so that the player is in complete (or as complete control as possible) of the production of said item.
ive also always wanted to see some kind of swordfight/fencing game, where the player controls the sword with something working similar to the gun in duckhunt.