Well perhaps Exodus3000 could state if I am correct or wrong.
It is my understanding that everything counts. The combined settlements count will increase the strength and defense of that alliance. The higher the settlement count of a alliance the more the increase will be.
This would be extra over the members personal stats that also influence the attack and defense. That while a level 20 vs another level 20. Has settings of 50% ratio. The members personal stats including mars dollars. Together with the alliance stats can influence that 50/50 setting to be greater or less then the basic 50/50 for equal levels attacking or defending.
I would hope that is how it is and I just didn't realize it, but I don't think the 20 vs 20 battle or 5 vs 5 battle for that matter is anything more than random...as stated in the rules. SO to say 50/50 chance of winning is misleading. You only have two possible outcomes...win or lose so that can be considered 50% odds yes but how often will the win come up is most definitely not 50% of the time. It's random wins and there are times when my winning far exceeds 50% and then there are days when my wining is lower than 50%.
The odd thing Sly, is you and your alliance far outweigh my stats, but most of the time I would place money on a victory over you in a settlement attack. Other less "well off" players redily kick my Seal Clubbin a**...even with lower stats than you. I stil lhaven't fully wrapped my head around it all and at times just seems like a crap-shoot.
As far as I can tell from the rules page the only effect a big alliance has over others is "influence".
"""Alliances: You can create or join alliances to increase your influence over other players. The more players in your alliance, the more influence you will have. There is no limit to the number of players you can have in your alliance."""""
Whatever that influence is has yet to be revealed afaik.
J