I'm getting jealous.
Also balancing this is very hard, because zk units and structures are so versatile, some things even replace each other functionality or may not perform good without being accompanied by something certain.
Also this game mode sounds more like "there is a team of city builders and team of raiders".
But here lies the problem. Almost anything in this game can encourage players to pork like mad and this later turns into the problem of performance.
Perhaps if it was more dynamic. For example like this:
The map is divided into 4 sectors.
a) Last castle area.
b) Middle castle area.
c) First castle area.
d) Attacking team spawn box.
Both teams can build anything, but not silencer and anti-nuke (you will understand why later).
Sectors a and b and c are separated by giant wall (it should teleport units back if they try to cross it).
Defending team stars in attacking team's spawn box and are given 30 seconds to run into the 1 sector's castle.
Attacking team starts in the attacking team's spawn box but their commanders are T1 and spawned with 30 seconds delay.
The game initial timer is 60 seconds that serves as a warm up, during which defending team needs to get into the castle.
After they get into the castle the walled are erected up automatically and any attacking unit is teleported outside of castle into sector D, and dead attacker's are revived, any dead defenders (team having 0 units) are moved into attacking team (yes for the lulz, defenders become attackers once they "resign", think of it like zombie survival?).
New timer is 5 minutes, both teams are permitted to build anything, but neither team should be able to cross giant wall, any unit trying to cross it should be teleported into it's team's home area and nothing should be permitted to be build on wall.
After timer reachs 0 wall becomes "normal sized" and unit's are granted permission to engage.
This is where
siege begins!
Timer is something like Grace/2 or /3. During this time attacking team should try to annihilate everyone inside castle OR! the wall separating sectors B and C becomes normal and unpassable for attacking team so they are able to retreat, naturally any defending team (not allyteam) that lost commander and all units (and couldn't retreat) are granted second chance as attacking team and are granted another commander (they start in attacking team spawnbox, obviously some of defenders become attackers).
With each progressing area gracing period and attacking period is doubled in time. Also the amount of enemies you should fight off is increased as much as bad you play, if you play good you either safely retreat into inner area every time and noone dies or you totally annihilate attackers.
The last area rules are different, after defending team (any survivors) get inside the giant wall is back to separate both teams for like 10-20 minutes. But as well as unselectable silencer (or multiple) is spawned in the castle with 100 nukes ready but emped for grace timer + attacking timer amount. Meaning you will have to defend it at all cost and use it to annihilate everything that's attacking you.
Naturally because attacking team can't have anti-nuke. The defending team can win by either overwhelming attacking team during B, C sectors or by holding A sector and firing nuke eventually.
Now, this is very hard to balance because naturally defending team is limited to it's castles while attacking team are gaining map territory size advantage, but it may be ok to just make castle's mexes while they belong to defending team produce 1.5x 2.5x and 5x metal during C,B,A sector stages respectively.
The joy, if you survive good, you get the chance to rebuild and try again at defending more cruel and aggressive enemy.
Naturally it may be possible to make an unlock system for both teams during all 3 stages of siege, so for example during first stage no striders and expensive defence as well as econ structures can be built (possible no air/gunships), during 2nd no striders, during 3rd stage probably everything can be built.
Now that is a wall of text, but if you read that, you may understand that I like complex games.
