Okay I have alot of idea's but heres alot (Its in groups Time,Biomes and addable stuff)
Biomes:Swamp,Grasslands,Water,Hearthlands,Darker Grass about the swamp it needs more scaryness in the swamps add more of the bigger trees and add some new creatures perhaps like aligators that you can kill for Aligator Scales (for a lil Bling Bling) and meat and add some snails stuff like that.In perhaps the grasslands and darker grass there should be waterfalls and pretty stuff like that. and water there should be lillypads (study) and frogs (study) the frogs are similar to the toad found in the swamps accept they spawn on lillypads and near water (forage lillpyads to get a frog) or just catch a frog. exactly as toad accept you can Butcher it and get frog legs, frog skin and frog eyes. (Frog Skin and Eyes for study and legs for food) Must cook though.For time there should be clocks like with an arrow or something that faces the time and you have a body monitor or whatever when in the day (this is add-ons to) of Summer if it goes to red you overheat u must drink something or stand in the shallows to lower it (must have tempraturess to if so another add-on) and in the winter if it gets to cold and your out at night you start to freeze when your body goes full ice you start to lose health and need to go inside
Seasons (goes with the temp and stuff) add stuff like in the Summer you can find like bear caves that you can go in and get like bones and stuff from (need a torch etc) and in the winter if you go in you will be attacked by a bear unless you sneak passed them (sleeping bears) and add like snow if you stay out you start to freeze.and stuff.
addable stuff eh ive already talked about alot of it but heres some more:Koi Ponds,Rain,Snow,Waterfalls,Rivers,Gunpowder,Musket and thats all i can think of accept (Greifers may like this) Flint and Tender use it to burn Wood and stuff like that especially homes (I would hate but makes more realistic) and Water buckets can put it out.And it can also lights a fireplace (100 Bricks+4Wood is brick fireplace and 125 Stone and 4 peices of wood for a stone its for temps if you start to freeze you go near one (cant be picked up must be placed in a house oor build a stone mansion that comes with one)