i wish i could code :c

Animation change under the influence (ive stated this before, but still)
not only do the animations change, you get certain buffs/debuffs depending on what it was you took
stimulants will increase your attack speed (melee and ranged) and decrease your stealth
depressants will decrease your attack speed and increase your stealth

Happiness (also stated before)
100-75%: your persuasion abilities are increased by 50%
74-35%: neutral, no buffs or debuffs
34-1%: your persuasion abilities are decreased by 50% and your walkspeed is decreased by 5%
0%: definitely a bit dark but you've got all the debuffs of 34-1% along with occasionally pausing to look at your weapon, with that increasing every 2 days. if you reach 0% and dont bring it up past 5% for 2 in game weeks, your character falls to their knees and takes a weapon from their inventory, ending it once and for all.

Temperature gauge+seasons (definitely not original, but ive never seen it incorporated into the genre im mentioning [shooter])
Depending on the time of day, the month, and the armor/clothing you have equipped, this will either go up or down
Hot (75-100%): slight animation change along with a risk of taking 1/8th of your health worth of damage every in game hour (simulating heat stroke while not immediately killing you), this risk increases in chance depending on how high the percentage of temperature is (75%=10%, 100%=50%)
Comfortable (60-40%): no change in anything
Cold (25-0%): same as hot however simulating hypothermia while not being retartarly overwhelming
Cold can be negated by standing near a fire source (this includes flamethrowers i have no f**king idea how i would code that) and hot can be negated by being in a water source