1: Food,pelts,Hide: Make food,pelts&Hide STACKABLE (stackable till 64) cause i allways get problems when i go for a hunt, after hunting 4 animals my inventory is full so i need to go back to my house to store it.
2: Animals&Water: make bigger rivers with animals like alligators, make more animals who attacks back, only Deers&Boar's attacks. and maybe add fishing?.
3: AnimalHealth: give animals more health every animal is 1 bow hit, example: a pig is the same health as an bear thats not good how harder it is to kill an animal how better stuff u get.
4: Grass: Make the grass a bit smaller cause when i chop a tree i cant really see the log's.
5: Traps: maybe add some traps to kill animals so you're not forced to always make a bow xd. and Maybe traps in caves? ;).
6: i found a small glich for mining/chopping works also vs animals see video's>> : TREEMINING
7: Seeds&Tree's: do that seeds grow with water.
8: Day&time: play a bit with the time mate, don't make it able to sleep when its night you must walk with a torch or you must just stay at home.
9: Weather: add snow,storm/lightning,sun to the game so if its snowing you maybe walk slower just guessing xd, if its raining you need an umbrella( and if u dont have you wil be slowly damaged) or you need to hide in a cave, if there is lightning it has a chance to hit your house/buildings and than you need to extinguish with a water bucket.
10: Taming: Maybe make it possible to tame animals with arrows to make them unconscious (would call those arrows Taming Arrows) and i should add Tier's for the Taming Arrows Tier1: nonattacking animals Tier2: Attacking animals
11: DeepOcean's: maybe make some LARGE ocean's where you can find crystals, which are rare to make special items and maybe add sharks in only the deep ocean's.
12: Energy,Electricity&Windmills: maybe add Energy,Electricity&Windmills to the game make a refrigerator that must be connected with Electricity, that means make food wil dry out if you leave it in a chest, and maybe do after killing an animal and taking his food all foods wil dry out in 15min.
that was it for now hopefully i helped you alot with idea's
good luck developing mate!