Ok You know how everyone wants zombies to attack your base right? Well all that base building would attract a lot of zombies after a while. My idea is that boarding up windows increases a invisible bar that turns green, 1-2 zombies will take a look, maybe even knock there heads around, if the bar turns yellow, maybe a 10 zombie hoard comes by, by this time you should have built a wall right? Then if you make more stuff, you get into the red, a zone of zombies comes and attacks. Waiting in game days will decrease the bar. And maybe ingame you can get a skill that shows the bar? That means that players that have a good base up can build a bunch of chairs and stuff and trigger attacks