[PvK]

Damage resistance: I think 100x the current levels is completely reasonable.

Reproduction: Changing the number of pop units this way is actually going to reduce the repro rate rather than increase it, because reproduction rate is linear except for the rounding error (minimum +1 per check). However, as I pointed out in Proportions, the default set's base repro rates are about 10x faster than actual human industrialized reproduction rates. That's why I set the repro check frequency to 10 (once every 10 turns) in Proportions.

Range check error: Tell MM and send a saved game, and he might fix it.

Overall, this is a nice idea, though I don't think it's a lot different from what I am doing in Proportions - it just has higher-grain less abstract numbers for population. I don't think of population units as necessarily representing one million civilians in Proportions. To me they mainly represent a level of effective workforce, including their equipment and survival necessities. The fact that they double in one year definitely does not represent in my mind that they reproduced and raised and educated childen at that rate. I think of it more abstractly, and I assume that there must be numerous small civilian craft that transport civilians and goods around (for example, this is the only way blockades make any sense). The natural population increase may take this into account.

In fact, I recently had a slight misgiving about how literal my treatment of population in Proportions is, compared to the following interpretation:

Another way to think of population is as if they are 1000 people each, but without increasing their numbers. In this interpretation, what they represent are 1000 highly-trained, educated, appropriate-age, healthy, colonization-equipped personnel who are under the emperor's control. Civillians who are not highly-trained, have health or age problems, or who for social reasons are not ready to serve as colonists, are not represented by populaion units (maybe by facilities, or by nothing). That is, they only represent the people who matter for the purposes they are used in the game.

Anyway, there are a various interesting ways to interpret and represent population. I'm pretty happy with the way Proportions works, but I'd be curious to see an attempt like Geo suggests here, too.

PvK