These could be another type of badge that you get from npc planets.
Doesn't nessessarily have to be green.

Badges aside I like the idea. Would add a nice little twist to the game.

i'm glad this has come up again. i suggested this back in december of '10. yes, this would add quite a bit of fun to planets. an additional point that i dont think you touched on is what would be on the planets. i suggested that npc races controlling them would have specific buildings unique to this addition. For example, a lazuli controlled planet would have a lazuli refinery on it. Now with the mylarai extractors, these additions would be much more attractive to people who capture and abandon planets. they could strip the planet of the unique structures and then ditch em. i think either a 25/75 defense/production split would be nice, but even up to a 50/50 split between the two would be cool. give us a bit of challenge. Also, these planets should have NPC guards. they can either be what is currently in the game, or they can be <npc race> sentinel that would drop either new planetary debuffs (maybe only effective against npc planets) or new invasion attack modules/ship buffs. i miss the stryll pathogens, that reward wasnt buffed or even included in higher level versions of that npc.

thats a good idea. have the sentinels spawn more npcs to guard, as that could be their ability. you have to kill the sentinels first, and then contend with the 'normal' guards.

and sadly, no... i had 2 pathogens but i accidently used one, so i'm saving the second one for my cargo museum. theres no invasion attack buffs dropped from npcs after that npc evades scans (i think its 150? its been a while). wish that problem was fixed, and that graxis had an upgraded version that dropped upgraded prisoners and upgraded pathogens (9 rank points, and say 500-1500 invasion attack?)

the only thing is that with the legion oriented takedowns of planets, that falls more into the NPC bases category, which i suggested around the first or second day of base combat... it would be for people that are pacifists, and maybe require dark badges to scan for instead of reds.

let the size of the planet determine the strength of the guard(as well as tech tier of defence structure), along with a certain ratio of the area being used for defence, it should be balanced size wise. Perhaps size also determines the "legion boost" it would get

And if richness reaches mega, generate NPC guard ship depending on richness, for example for each 2x spawn 1 guard (14x mega would have 7 guards)

humm... what else...

Based on whatever other property, the planet can also have buffs applied to it. For example, terras can have full sets of T.O. buffs just cuase~ I would think this function(that is random buffs) should apply to any upgradable type of planets cause...well... they can go above the regular max. (not couting hyperterra, rift or dyson ofc)

Although I would think all those planets should be fully immuned to arts.... otherwise all it takes is a few bio vap and sabs and the planets is....
I mean sure, it can have some special structures, but~ it won't last...
Or at least it needs to be "repaired" every hour....

You know I would not mind fighting some boss npc to clear a found planet -- if better planets were generated on average.

ok, but how do we determine the level of npc that is guarding that planet? if a Rank 5 finds an Npc guarded planet is it going to have 10 defense on it or what? Also, if someone else finds the same planet is there going to be a different level Npc?

Possibly instead of just green badges or a new badge, a variety could be given.

Few examples of planet invade badge rewards:

Dark Smuggler, RSL : 5 Dark badges

Vygiod, Kroyn : 5 Blue Badges

Crimson Blades, Konqul: 5 Red Badges

Human, Xecti: 2 Green Badges

Prejor: 10 Silver Badges

As an aside, I would only have Prejor hold exotics/Dysons, and be defended with at least 2500 attack and defence (5K invasion defense total)