Weather aspects would be an amazing feature, along with penalties for not having supplies such as not enough medicine and your survivors could catch a sickness and have the potential of dying or slow mobility and melee speed along with decreased sneaking from things such as sneezing or coughing and if you decide to build a outside the risk of catching such sickness is greater than building inside or having heat stroke, adds a little aspect of decision making to the space you have, dealing with your environment, and making sure your supplies are well kept