Thirst - You now have a thirst bar positioned above your hunger bar. You must keep it replenished by drinking fluids such as water. The bar acts much like hunger; if you fail to keep it full, you will begin to die of thirst. You can get quickly get water by crouching and right-clicking a water source block or by drinking a bottle of water. However, if you want to avoid the Thirst effect purify the water through smelting or drink a potion. The Thirst effect causes your thirst bar to drop faster, much like Hunger for the hunger bar.
Temperature Mechanics - Your body temperature will be influenced by how hot or how cold your current biome and the blocks around you are. Vanilla armors will increase your temperature as well as how fast you heat up. Wearing wool armor will increase your resistance to cold temperatures, and using stiffened honey armor will improve your resistance to heat. If you get too cold or too hot you will get hypothermia or hyperthermia respectively, which act like poison by killing you until you reach half a heart. By default, your temperature is displayed as a tint on your Hotbar but can be changed to a bar meter atop your screen or number value in the config file.
Sleep/Energy Mechanics - You will now require sleep to function properly. If you refuse to sleep for days at a time, your body will start to shut down. This will lead to debuffs influencing your movement speed and other functions, as well as restricting your vision gradually. You can drink caffeinated/sugary drinks to grant yourself the Energized effect, which reverses tiredness and gives various effects.
Stamina Mechanics - Certain actions you perform in your world will now lower your new stamina bar upon performing. Your stamina can be replenished by standing still, walking rather than running, or laying in a bed. Sleeping fills the meter completely. When you run out of stamina, the meter will turn red and you will see three red stamina slots. This is your reserve stamina, which is a clear indicator that you will die if you work your body much more. Once your reserve stamina runs out, you will swiftly proceed to die of exhaustion.
Each and every mechanic can be disabled in the config file. Some can additionally be altered to change how much certain aspects of the game impact Survive's mechanics. For example, you may add modded drinks to the thirst list to allow them to fulfill thirst needs (some mods are included by default).
[As of version 3.1.0 some configurations are bugged or broken but will get fixed in future updates. This may apply to past versions as well.]
Potential Features (May come in future updates, but are not confirmed):