It would be interesting indeed. I would only have one suggestion: you should either ban Ancient race or reduce/forbid warp openers. Otherwise it would be quite easy to have a look at the planets list, figure out where are the other deities (very easy as the starting planet is a Sphere World, but it would work as well with standard planets), and open a wormhole or two to their systems.
Obviously, in such circumstances the younger races would not be used and the fight would merely be between a few systems and Stellar Manipulation. You could even completely ban Stellar Manipulation, if only destroying stars would not be a very suitable power for a divinity.
