Townfolks - Citybuilding pure card game

To evaluate the idea, we need more detail. What are the sorts of prophecies? What are the mechanics for generating food, more townspeople, defenses, etc.

There certainly are a number of town-building worker placement games, but adding the prophecies might be an interesting twist.

I would suggest, however, that rather than a single prophecy that will definitely come true at a known time, you make this a little random. For instance, you might have 4 prophecies, dealt out in two pairs. Call them A, B, C, And D.

Each year, roll a d6.
1: A occurs, B is discarded
2: B occurs, A is discarded
3: C occurs, D is discarded
4: D occurs, C is discarded
5 or 6: No prophecy occurs.

Any prophecy that occurs or is discarded is replaced with a new one from the deck. Any one that neither occurs nor is discarded stays where it is, perhaps to happen in a future year.

This would mean that the players can work towards one prophecy and hope that it eventually happens, or they might find two prophecies that are similar enough that they can kind of work towards both.

You could make the selection of the prophecy to occur be more complicated, and involve something that the players can affect by having their workers spend time praying or sacrificing resources. This, of course, would have an opportunity cost, since it means that the workers aren't doing something more productive. Of course, it should not be possible for any player to guarantee one prophecy over the other, only influence its likelihood. Two players might get into a war trying to cause competing prophecies to occur, to the benefit of the other players.