I like that in Sim City 3000 you can make deals with other towns to say haul ALL of your trash away for x amount of $$$ per so many "unit". Great concept but it sucked to sell [img]/xxx.gif[/img][img]/xxx.gif[/img][img]/xxx.gif[/img][img]/xxx.gif[/img] to other towns. You had to make deals to give them X amount of electricity every month for Y amount of $$$. X was usually every bit of whatever was not in use. Great concept and executed nicely for giving other towns jobs in your town but not the other way around.

In RPGs the 3 that stand out in my mind are Chrono Cross, Xenogears and Lunar for limiting your levels to make it challenging. In Cross you could not go beyond a certain level. In Gears your mechs were limited in ability to the items you could buy. In Lunar the enemy level was based off of your level so you couldn't over gain.