Drunkenness

Alcohol is a special poison.

Basics
Roll a Con Save against the drinks DC + the round of drinks you are on. Add optional Mods to your roll depending on the circumstances, like a -3 if you aren't used to alcohol or if you drink on an empty stomach, or a +3 if you drink often or if you are a dwarf. Failed saves make you gain one level of inebriation.

Drink DC

 * ale, cider, [...]: DC 11
 * wines, mead, [...]: DC 12
 * liquors, [...]: DC 13-17
 * dwarven spirits & other specials: up to 25

Tipsy

 * +2 to performance checks
 * disadvantage on insight checks
 * PC might act more brave and open than usual

Drunk

 * advantage to Saves against being frightened
 * get poisoned condition as long as this status persists
 * PC might cast some more inhibitions aside

Hammered

 * immunity to being frightened
 * resistance to psychic damage
 * still poisoned
 * speed is reduced to half
 * disadvantage to all Dex, Int, Wis and Cha saves
 * PC might have a severe lack of self-control or might just pass out at some point

Blackout

 * The Player loses control over the PC. The PC collapses or alternatively the DM could role on a random table or make something fitting up what could have happened in this time-frame. But the PC won't remember.
 * get the hangover condition afterwards

Hangover
After failing Save while the Hammered stage is already reached, you will suffer from the hangover condition as soon as all drunkenness has worn off. Hangover will give disadvantage to attack rolls, ability checks and Saves against being blinded. It is cured after finishing another long rest or through Lesser Restoration.

Curing drunkenness

 * certain drinks can reduce drunkenness
 * Lesser Restoration removes all drunkenness and resets rounds to 0
 * each hour without drinking reduces number of rounds by 1
 * each 2 hours of not drinking will cure one level of inebriation