This isn't exactly a want to play past no energy rant but I thought it would be interesting if OOO would experiment with different payment models for adventuring areas. Currently we have the dungeons which have players pay in energy before they can start playing but what about a dungeon that lets players enter for free but they have to pay energy every time they want to get any rewards? I imagine it would work something like this:

Implement a large open area players can explore populated by monsters which drop no loot. Players explore the area looking for hidden treasure chests that require a certain amount of energy to open but can drop fabulous treasures such as items and recipes. The deeper into the area the players adventure, the more difficult the monsters but the greater the loot from rarer treasure chests and the more energy it costs to open them. A fun distraction for players with no energy left but still want to play and can possibly encourage players to purchase energy if they find a rare treasure chest they want to open.