I haven’t tested the game, but I’m closely watching the progress, especially because I was describing almost the exact game to croatian gaming community a day before I found it.
So anyway, I have tons of ideas, but I’ll just separate and explain a few of them.
In-game clans: removes the need of those annoying faction/towny like mods for just “living” together with your friends or friendlies. Starting the clan could be free (or certain prereqs), and it could “grow” stronger or weaker depending on the number of clan kills/deaths and successful base defending. Based on the “strength” of the clan, the rewards could be (simultaniously) expanding the base or more HP on clan-made structures (or even adding more base structures like spotlights, electric fence, explosive barrels…). The more people in the clan being successful, the stronger their base is, and more fun it is for both them and the raiders. It also eases the storage and door sharing between friendlies. This, and the pressumable fact of having aggressive zombies in the game, leads to the next one.
Clan size aggro, true survival: Ok, so we have 20 people, building something like a town, more and more people are joining every day, raiders are rare and shot on sight, nothing to be afraid of right? WRONG. This idea is kinda mathematically hard to define while programming, but would make for much more interesting and realistic experience. If you are a member of a clan, and you have a marked spot for your base, having it grow more and more along with the population, makes the zombies go for the belly. Every night you get invaded by huge amounts of zombies, depending on the online clan members. Amount of zombies multiplier could start with let’s say x1.60 and for every clan member, it would rise by x0.20, and for every base “upgrade” (check the first idea), the multiplier adds x0.50. During the day you could freely roam, scavenge, raid big camps, but at night you really have to survive, and do it together. Maybe dispatching a few spare members to go out scouting or raid smaller camps, but remember that they still add to the zombie multiplier, no matter how far they are. If you want to survive together, stick together.