An option to replay Stardew Valley in hard mode after reaching a certain point in the game would be cool. Making the game more challenging would make it that much more exciting to play and prolong the build up stage. I like the suggestions of Natural Disasters, Joja as a really evil antagonist, or the dept contract twist. But as this is a Farming Game, aligning it to the reality of farming might be quite a challenge already. Energy Balance: Just like in real life, the only way to get energy for activities is by calory content of food eaten (not by sleeping), you have a small continious decrease of energy (for body function) and need more energy the more ardous the task. You would need to eat every morning and over the day. You would even need to store food to fuel all the activity you are planing. No food would mean no energy for tilling, chopping and watering so easy food provision like foraging or fishing would become more significant for survival. Stocking up (for the winter): is a huge part of farm life. The concern for supply of food and wood for the next winter needs to be pressing. My fireplace should consume (for instance) 10 pieces of wood per winter day (and bad weather day?) or else ... sickness. A cellar for storing would be needed, maybe some woodbin for firewood. Perishing Food: a farmer can store grains for years, potatoes, carrots and apples for a year or a half and everthing else has to go into the preserving bin after the season is out. Seasonal food is even more awesome if you dont have it all year. Death: If you die from sickness or injury you need to reload the morning. The Hospital is for health care not for teleporting and reviving. Overworked? Not slept enough? Eaten a poisonous mushrooom or got kicked by a mad slime? Go to hospital already! ...before it is too late. Reward: hardmode should offer a special reward for your trouble like more building or marriage options A well balanced hardmode might give you the kick of a survival game and enhance the significance of some overlooked but already implemented aspects of the game.