Harry Turtledove's novel about a version of Mesopotamia ruled by Physical Gods.
Between the Rivers contains examples of:
- Gods Need Prayer Badly: It appears to be the case that the gods depend on their worshipers, though part of the plot is that the gods have taken care to prevent any of their worshipers suspecting this.
- Physical Gods: The cities are ruled by gods. These gods posses a variety of divine powers and posses somewhat humanoid physical forms whose exact sizes and anatomy vary by the occasion. They seem to be ageless and are extremely difficult to kill.
- The Promise: Sharur in a grandstanding moment vows that he won't marry his sweetheart until the completion of the trading expedition he's about to embark on. It seems like a safe thing to do since it's a routine expedition and he wasn't planning to marry her until after he got back anyway. But then the nation they were going to trade with unexpectedly puts a trading embargo on the Sharur's city. And the god (Engibil) he swore by is real, interventionist, and quite willing to make the vow stick.
