Black Forest is a turn-based game. Every turn represents one day in the game world. It is split into two parts: Day and Night.
During the day, every living villager can complete one action. Actions are given during the turn period, and then resolved simultaneously.
During the night, the villagers are hiding in their houses, while wolves, bears and unspeakable monsters (at least if you ask the peasants) come out of the forest.
Typical games will run one turn a day, so effectively they run in real time, giving every player plenty of time to issue his actions.
There can also be games with faster or slower speed, for players who wish for a more rapid or more casual experience.
As if everything were not bad enough already, winter is coming.
The first 15 days of a game will be played in summer, where everything is warm and friendly. Relatively at least. But after that, it is autumn. During autumn, there is less food to be found in the forest. Gathering food in the forest will only gain you 1 food. But grain has its main harvest season (8 food instead of 5 during summer).
After 30 days, it will be winter. During winter, gathering food in the forest is pointless and the few winter crops that can be planted yield significantly less harvest, only 3 food. Note that the day where the field was planted determines how much food it will yield. On the plus side, this means you do not have to worry much about manning the well during winter, it is wet enough as it is.
Day 45 is the last day of winter. If you survive this day, spring arrives and everyone who is still alive has won the game.