Ok, enough with the folks saying Force Fields IS cheating or some such nonsense.
The real problem is that:
The game designers have a bad idea, "the zombies must be allowed to come at the player from all points of the compass", and so they design the AI to spawn them in such a fashion. the result? If an intelligent player builds a base that allows the zombies to walk in the front door, but no other way in, the zombies will just try to beat their way through the players walls, and make such a path.
My outer walls stop the zombies.
Period.
Full stop.
When I build my defensive position, I'm going to leave the enemy just one way to attack me, and I'll throw in every kind of way to slow them down, and make them pay the price of getting to me. Because I want to fight/kill all the zombies, 'up close and personal' as it were, and building a big base with just one way in causes the badly designed AI spawning to break down is not my fault.
I had a Horde Night base in my last game. No surprise there. I initially left the zombies 4 ways into the inner base (Just like now.). Then I heard good things about "Force Fields", and experimented with the, by surrounding my entire base with a 5 block deep, 3 block thick force field, outside the walls of my base. I then also walled of 3 of the 4 ways into the base, with walls 3 blocks thick by 5 blocks high. Keep in mind, those new walls were the weakest walls my base had.
The result?
Horde Night broke.
Why?
Because the zombies couldn't attack from all directions of the compass, and if they had to go all the way around the base (because they cannot just be satisfied with spawning in one direction), then they would happily spend all night trying to break through my outer walls, with only very small numbers actually spawning on the correct side of my base (the one I left open), and thus, and thus Horde Night was ruined.
The problem isn't one of the player building a base with just one approach, it is one of pathing, and need the zombies to just spawn in one direction if the player properly builds their base. The Horde nights where I would end up with jut 2-3 zombies making it into my base, and the rest were just AWOL. I had to go outside the outer walls of my base, and lo and behold, the the rest of them were, uselessly beating on the outer walls (the closest thing they achieved to a breakthrough was a two block high, one block deep hole, with a one block high, one block deep start on the second row of blocks).
The problem?
Remember the 3 block thick, five block high walls, the weak points, that I built over 3 of the four initial openings, between the building of my bases 4 buildings? Those were not being especially targeted, as the fastest way into my inner base, no, they were just trundling up to any building and trying to achieve a 'breakthrough' where ever the spawning strategy initially put them. The problem, all 4 of my buildings were built on solid foundation of cobblestone 4 block high, and you guessed it, none of these four buildings were a measly 4 blocks thick, but rather 13 blocks wide, and 30+ blocks long. Other than the mineshaft down to bedrock, all of my base sat on top of these foundations!
There is no way the zombies should be trying to spawn all around my base, they need to have their scouts, as well as the "Spies in the sky", tell them where they can most easily enter the player base, and just spawn it that direction.
Keep in mind, Horde Nights prior to base completion, are not going to be locked out in such a fashion/degree, but by later Horde nights, the zombies should have learned where there is a way in, and where there is not.
So the problem is one of pathing, not base design. A small base has no problem, as the pathing is easy for the zombies to reach "the way in", but when you build a bigger/better base, they need to have a way in, and just spawn in that one direction. Give me an AI that spawns in that ONE direction, and all is good. All the zombies will meet me, and then meet their maker shortly thereafter, and then their replacements will begin this process all over again. Do that, and we have a good game, and I won't continue using Force Fields, do it NOT, and just put up with the Force Fields.
Now, if anyone want to critique my actual base design/layout, that is different. Look at what I have build, realise what I have done to accommodate an AI that is built around they idea of "all around is sound" as a spawning strategy, instead of building an AI, that uses fog of war, and tries to scout out where a players base can most easily be entered, and just concentrate all spawns in that direction. Presto, all problems solved, and players can design bigger bases without Horde Night getting broken, because the zombies won't spawn in a direction that they cannot path to the inner base, so they just instead spawn all over the place, and spend the rest of horde night beating on the outer walls, until I leave my base, come find them, and kill them.
All that being said, that was last games experience, this new game, I am building a much smaller Horde Night base, where the zombies bad AI spawning system allows them to spawn in any direction, and still path to the inner base, but denying them an unneeded/unwanted capacity to attack me from behind.
Now, anyone want to continue discussing my bases construction/layout?
I have to admit, I'm not only willing to share (with pic/videos/grid plans), but am actually eager to do so.