They currently only have one upgrade option, and that can only be used once (not counting rifts). Let's see what kind of ideas we can throw together to boost them.

What I have in mind to begin with is converting them into a space station. +2 size, +3 resources, 1500 attack and defense boost, make it a mission line to follow the irradiated missions. It's a pretty big upgrade, but getting all those Iso-Runners dead is no mean feat, either. What else can you guys come up with?

planetary cybernetic net : transforms metallic planet into a cybernetic world run by an advanced AI
+2 size , +2 to all resources , +1500 att/def/cloak

OP ?

+1 size, +2 Mining/Research, +1000 Atk/Def


+2 size would allow for mega colossal planets very easily, I have a few very massive metallics sitting ready, +1 size is more appropriate if you ask me

I'd like to see something more radical...

I like your idea of space station but it seems to big especially with planets being Very Massive.

How about getting an item that gives us the choice between:
Specialized Metallic - Mining: Size Massive, +1 mining, +1500 cloak/defense, Permanent Ultra Pure Deposit ability (Mining +20%). Looks like a cross between an Ecumenopolis and a metallic planet.

Specialized Metallic - Research: Size Massive, +1 research, +1500 cloak/defense, Permanent Planetary Cybernetic Network (Research +20%). Looks like a round Matrioshka Brain.

I think the idea of finding NPCs after doing the irradiated planet mission makes sense.

I'm bucking the trend of +size planets and saying this upgrade will make all metallic planets getting this upgrade massive. So yes, a very massive will become a massive but an average will become a massive. This will make planets that are normally ignored because of size become viable and valuable.

Gravetic Condensor:
REDUCES size by 1, but adds 5 to all productions and 1000 to all stats. Makes a Hyperdensity World (Name may need changing)