I think we should have nicer looking maps.

How about a less homogeneous world?

How about a resource that is not a resource? Rivers: A tile with a flow direction. Pushes creeps 1 tile downstream per tick. MOVEs happen after the push, so you always go at least one tile when crossing a river. Roads on a river tile remove the push effect. (bridges) This simple mechanic would provide massive room for complexity, and how you distribute them gives lots of options. If you have multiple rivers flow into or out of a room it becomes capable of controlling more territory more efficiently. But it also introduces a security weakness. Someone could setup in a room upstream and spawn creeps in the water with all attack no move, letting them get a cheap beachead.

I enthusiastically support different color pallets.

From the darkest depths of the locked sectors a beast awakens. Infuriated by the exploitation of the land, the serpent and its sisters set out. Drawn to the loudest most advanced industries, they aim to exact a bloody toll.

Physiology:
Consists of one Head creep and N Tail creeps.
All segments have the same parts.
Serpent moves at speed of slowest segment.
Tail creeps follow the segment in front of themselves.
Tail creeps never attack.
When any segment is destroyed, all remaining segments parts get doubled stats.
When a segment is destroyed, the segment behind it becomes a head segment.

Rational: I want to add a npc enemy that rewards good code instead of good economy. Adding fun complexity to the game without to much coding effort on the devs part.
The idea is that the beast starts out easy to beat if you time it so that all segments are destroyed on the same tick, but if you have code that does not handle the serpent then it will get exponentially harder to defeat even for a well developed base.
Additionally, you can strategically not completely destroy a segment to make the beast slow to a crawl.