I joined the game in June, and when I woke up a few hours ago I saw my dear Merykor with only 18mil survivor, out of 786mil population.

I am entering the community just now, and I didn't know what was happening, if the effects were permanent or anything. Something that should be fun became just confusing for me, until I got a grasp of the situation.

The worst thing is: I decided to research a cure, but it's stuck at 4.2% research, with my only weapon being a L1 Strike Force. My L2 Specialists are also stuck at 65.7%, and recently all my zombies were killed, so not only I couldn't cure anyone, having a laughable killing capacity, I couldn't even infect anyone. It very quickly turned from confusing, to interesting, to boring.

The worster thing is that it's the ninth edition of the event, and it would be pretty simple to fix.

First, how to warn people who don't participate on the community?

Having this type of event is great for the community. It can convince people to make part in it, but if they are stuck in ignorance and can't prepare, they'll be turned off by it. The solution could be as simple as journal headlines. Every time you decide on an issue, some headlines appear with news from your nation. I think it's a genius idea that could be better utilized. Imagine a headline that say "Cult says apocalypse is coming" a week or two before the thing happens, then "New virus revives dead cells" and so on.

Second, how to have a better gameplay?

This one would be a little harder to implement, but I would do it like that: issue based today's census. If you embraced zombies, and the horde superweapons being the easiest to have, today's census would be survivors. If you research cure or exterminate zombies, it would be infected. Also, the most important, the more dead people there are the more research and training should slow down, but never to the point of stopping or almost stopping. Is it more realistic? Yes! Is it more fun? No! The only thing that should stay as is is the hordes not being available anymore if you don't have enough zombies.

TL;DR: game has good ideas, bad implementation. Proposed solutions above.