Been there, done that. Base defence was like, left-click 8 times, then hit r. Rince and repeat until lag and zombies was gone.
Survival skills, not really. In my opinion, survival actually is to fight as little as possible , or find methods that put you, the player, at as little risk
as possible. In other words, kinda like min/maxing.
Fighting skills, maybe. I'm not denying it gives a certain thrill to run around on the ground at horde night, at least the first times one do it, and most
at the start of the bloodmoon. It's quite fun, but i am not considering it "survival". Just fun.
Even if this game become super-optimized to support massive hordes, players will adept their fighting style to match the horde sizes. Explosives can be
quite useful for large zombie gatherings.
It's quite some time ago i had fun with those massive hordes. It was in multiplayer too. And, it was where i first learned how to run and club zombies.
And, yes. That image just shows a roaming horde... not bloodmoon horde. Hiding image behind spoiler tag to not steal this thread entirely.