I used to curate a similar mod that increased planet/habitat size by constructing a building. And a script removed the building automatically, increasing planet size, when it was done. In that case you could modify the duration of the modifiers simply enough by modifying build speed.

But in this case, you could set up a redundant version of each expansion that applies planetary modifiers for shorter durations.

To prevent clutter you have a clause in the possible = section that says only the most advanced version is displayed.

I'm trying to work out how you could add a repeatable tech to reduce the time on the modifiers, and one for the time spent activating the edict. Anyone know the function I need to call for that?

I'm trying a Sol system no FTL playthrough. This should help.

Updated for 2.2, some changes due to planetary tiles->districts and edict->decision changes.

I'll be posting an minor update soon for 2.2..

mine and thank

Modified that planetary expansion now requires terrestrial sculpting, the same requirement that gives terraforming. Habitat expansion now requires Mega-Engineering. Tweaked planet expansion in progress penalty.

I'd say reduce the resource hit to about 75%, so that it doesn't totally cripple your early game, and reduce pop growth and building by 200% - or a flat amount of 10, if you can do additive effects on growth, because the highest I got was about 9/month.

I might even buff the influence cost a bit as well.

Already noticed that, on a personal side i've upped the resource hit to 150% might make 200% to zero out the resources including any buffs. The pop hit sounds like a good idea, hows 50% reduction sound or should I make higher say 75-90%.

What I found while playing with it:
The "no minerals and no energy" doesn't do the job. It hurts you very much early on, and not at all later on, thus you can just spam this later on (with about 3 planets you can keep a stable economy for 5 planets and still make a plus). Plus, it's not really all that bad, because of the way boni and mali work in Stellaris - additive. If your pops are happy (and/or buffed by traits/ traditions/ etc) enough, they still keep producing resources, not all that much tho.

So, what I would recommend for balancing purposes: Make it so that it just halts pop growth (and robot building time). It's gonna hurt you as much in the late game as it does in the early game, and it doesn't totally cripple your stable economy, but rather your expansion capabilities. Plus, you can easily buffer a heavy loss in energy for one year with some stock, but you can't buffer lack of growth.

Okay looking at both positive and negative random events that will occur on completion. eg. possible bonus extra tile or random resource found. And some negative ones like infrasture collapse and/or tile lost. What I've done so far is pretty rough and deciding whether to finish or wait till 2.0 update to finalise.

And in worst case - something like the ancient terraforming equipment event. Total failure, everyone dies.

Mmm That sounds interesting, like some kinda disaster that either prolongs the duration or causes the opposite like a lost a tile due to failure.

Just a thought for the future - what about "oh damn this went wrong" - kinda events? Kinda like tomb worlds... Thinking about cataclysmic earthquakes, devastating floods, and at worst, a ruined atmosphere...

Thinking of adjusting prereq's to need 5 pops and planet admin building as minimum for edict to appear. Any thoughts?

Feel free to offer any criticisms or wishes of things to be added.