New to the forum, don't really use social media so i didnt know where to post feedback to Firaxis. Played a game with the new zombie mode, myself, my friend and then a bunch of ai. Difficulty was not high as my mate and I aren't exactly civ masters however we got to the end game on quick speed and the game ended by score so it seems the zombies did their part of slowing everyone down. Problem is, i wouldnt say it did it in a very interesting way.
Feel free to share your thoughts in replies
Strengths:
1) It is fun to try spawn zombies on other players
2) Super scary seeing a wave of zombies come out of the fog of war in the early game
3) The concept, I really really like the idea of a zombie mode
Weaknesses:
1) First off this isnt a actual survival mode, it's more of a extra difficulty mode. I'd love a "survive 100 turns against increasingly difficult waves of zombies" game mode where you have 1,2,4,5,8,10, ect zombies appear on every 5th or 10th wave and they scale to your tech level so they stay relevant. having them just spawn randomly like they do now just seems to force you to put up defences and get more troops earlier. You could even add a scoreboard and make it a multiplayer mode so you get points by how many zombies you kill as well as other factors in the game. Maybe even limit the game to specific tech eras if it is a shorter game mode.
2) The zombies are legitimately a hindrance early (which they should be), on online speed they appear en masse between turn 13-16 for me and it is so overwhelming I love it. Unfortunately once you get some encampments up, build walls and throw some archers in cities/districts you basically rek any zombie that trickles in over time. Then after that zombies seem to just thin out for the rest of the game. There is no occasional horde that rises from the grave, only zombies in unowned land and zombies spawned by spies so it basically becomes a normal game.
3) Spies summoning zombies. It's a fun idea to slow enemies down but when 2 or 3 zombies appear and get instantly popped by defenses it's now a useless game mode, just tougher barbs spawning closer although they dont pillage.
4) Tile improvements, what's the point of them? You can put them along the edge of your land but as we established if you fill most of the land in the zombies basically cease to come from outside so those improvements are now useless. if you put them around your city to stop spies being effective then you lose valuable tiles.
4) Tech levels, the zombies seem to scale by global tech average which is fine normally until you are behind everyone else after a war went bad, then you find that the zombes are like a tank against knights, it's suuuuper unbalanced. Maybe a the base strength is based off average tech lvl and then a modifier is placed to increase/decrease the zombie strength based on the individual tech lvl of the nation fighting that zombie?
6) Fix the zombies capturing cities!! It's so weird and doesn't feel right. First off they reach your city, start smacking it and you dont lose any pop, i guess they all hid behind walls right? So then the city walls fall and the health starts getting brought down, pop should be dying and joining zombies? But then when the city is actually captured it just gets razed.... why? A whole city falling to the plague should either:
a) Spawn a massive horde of zombies, we talking 1 zombie per pop in the city or something to that effect, if city is over 10 pop then it spawns super zombies instead, maybe zombie corps/army so they slightly stronger? or a new type of zombie that is ranged or tanky. It should be punishing to lose a city to a horde that spreads infection!
b) If no hordes then the city itself should become a zombie city, one that spawns zombies reguarly and is a constant threat as the infected population wander out of the city and look for fresh brains, meaning you need to recapture the city to stop the constant spawn of undead or if you cant then you use tile improvements to wall off that city from your empire.
That's all I can think of right now. It's not a bad game mode it's just.... underwhelming. Like more annoying barbs.
Feel free to share your thoughts in replies

Strengths:
1) It is fun to try spawn zombies on other players
2) Super scary seeing a wave of zombies come out of the fog of war in the early game
3) The concept, I really really like the idea of a zombie mode
Weaknesses:
1) First off this isnt a actual survival mode, it's more of a extra difficulty mode. I'd love a "survive 100 turns against increasingly difficult waves of zombies" game mode where you have 1,2,4,5,8,10, ect zombies appear on every 5th or 10th wave and they scale to your tech level so they stay relevant. having them just spawn randomly like they do now just seems to force you to put up defences and get more troops earlier. You could even add a scoreboard and make it a multiplayer mode so you get points by how many zombies you kill as well as other factors in the game. Maybe even limit the game to specific tech eras if it is a shorter game mode.
2) The zombies are legitimately a hindrance early (which they should be), on online speed they appear en masse between turn 13-16 for me and it is so overwhelming I love it. Unfortunately once you get some encampments up, build walls and throw some archers in cities/districts you basically rek any zombie that trickles in over time. Then after that zombies seem to just thin out for the rest of the game. There is no occasional horde that rises from the grave, only zombies in unowned land and zombies spawned by spies so it basically becomes a normal game.
3) Spies summoning zombies. It's a fun idea to slow enemies down but when 2 or 3 zombies appear and get instantly popped by defenses it's now a useless game mode, just tougher barbs spawning closer although they dont pillage.
4) Tile improvements, what's the point of them? You can put them along the edge of your land but as we established if you fill most of the land in the zombies basically cease to come from outside so those improvements are now useless. if you put them around your city to stop spies being effective then you lose valuable tiles.
4) Tech levels, the zombies seem to scale by global tech average which is fine normally until you are behind everyone else after a war went bad, then you find that the zombes are like a tank against knights, it's suuuuper unbalanced. Maybe a the base strength is based off average tech lvl and then a modifier is placed to increase/decrease the zombie strength based on the individual tech lvl of the nation fighting that zombie?
6) Fix the zombies capturing cities!! It's so weird and doesn't feel right. First off they reach your city, start smacking it and you dont lose any pop, i guess they all hid behind walls right? So then the city walls fall and the health starts getting brought down, pop should be dying and joining zombies? But then when the city is actually captured it just gets razed.... why? A whole city falling to the plague should either:
a) Spawn a massive horde of zombies, we talking 1 zombie per pop in the city or something to that effect, if city is over 10 pop then it spawns super zombies instead, maybe zombie corps/army so they slightly stronger? or a new type of zombie that is ranged or tanky. It should be punishing to lose a city to a horde that spreads infection!
b) If no hordes then the city itself should become a zombie city, one that spawns zombies reguarly and is a constant threat as the infected population wander out of the city and look for fresh brains, meaning you need to recapture the city to stop the constant spawn of undead or if you cant then you use tile improvements to wall off that city from your empire.
That's all I can think of right now. It's not a bad game mode it's just.... underwhelming. Like more annoying barbs.