I like the game, but my issue is, I can get bored when the survival aspect is all taken care of. You become self-sufficient quite quickly.
Also, things like Infestations seem like way better challenges than base defense, since it doesn't need to be balanced around cheese designs.
I'm also all for choose-your-own difficulty kind of thing, but the game needs those available. Another thing the infestations (and building Tiers in general) do.
If I had to change the game in some way, it'd be fundamentally changing how the 7th day works. Change it to be a selection of survival issues each 7th day.
Each 7th day, the world presents a challenge, either instant, or ongoing, e.g.:
Feral Zombies (Same as now)
Weather
Deep Freeze
Very cold weather. Change the system to have ramping cold mechanics delayed or reversed by clothing, shelter and heat sources
Lasts up til the next 7th day
Crops stop growing or can die in this time
Water sources freeze
Increase in wolves
Storm
Constant rain and clouds. Loud.
Acts as a permanent night
Lasts up til the next 7th day
Cold due to wetness, but nothing like Deep Freeze
Heatwave
Extreme heat. Change the system to have ramping heat mechanics delayed or reversed by clothing, shelter and water sources
Lasts up til the next 7th day
Crop system changed to require water. More water needed in this event
Being in exposed sun can ramp up the effects quite quickly
Add a food spoilage system for anything not canned. This event speeds up that spoilage
Increase in vultures
Fallout
A wave of nuclear fallout passes over the map over the 7 days.
You need to bunker down while it passes or have the gear to survive it
After passing it, leaves a far larger percentage of zombies radiated for the remaining days
The wave is large enough that it takes a day to pass over any single area of the map
Raiders
I know we're aiming for them. But an event for 7th day around them would be good. For 7 days they launch attacks at various times
Unlike zombies, their main aim is attacking your base and raiding your stash, whether you're there or not
You get a warning within a couple of hours of attacks
After half the days have passed, their camp is revealed is you want to try to stop them at the source
The camp can be a literal camp somewhere
Or, a POI with raider spawns replacing zombies
The POI can be found beforehand, but isn't revealed
Feral Fauna
All animals are zombiefied for the next 7 days
Animals no longer attack zombies for this period, only players
Packs of various animals wander the world
This also includes flocks of birds
Animals are far more aggressive in this period and have a larger aggro range
Zombie Mutation
For 7 days, zombies get a mutator, e.g.
Head Shots - only head shots hurt them ( can still take off limbs)
Bullet Resistant - less damage from bullets
Tough - Bonus health
Burning - always on fire, but don't take damage from it
etc.
These mods could be configured to go away on the 7th day, or stack and fall off
e.g. if you set it to a 3 stack, the zombies retain the latest 3 buffs they've gotten from these events
You could make it so max stacks increase every X days to have a ramping challenge
Basically just things like this that up the survival aspect. When I say "7th day", I am referring to whatever the player sets it to, not necessarily 7th. Then they could enable or disable these events in options too. So you could, for instance, have a permanent Deep Freeze world, or a Raider world, or Wild World, etc.
For me, the zombie attacks on the 7th day are the least interesting aspect of 7 days to die at the moment