1. Send transports to invade.
2. Build Influence starbases to assimilate.
3. Build and place spies to sabotage.
4. Build a Terror Star and blow up the sun.

In the past I would build spore ships and spore them to death and then the planets would become my planets.

But now I go to war with them and then make peace by taking all their planets in the peace deal and win the game.

How you say! Make sure your Dipo is higher then thiers and don't break any trade agreements either.

When our Enemies win a battle, they called a Victory  

but when Saint Mina, Our Living Saint wins a battle, our Enemies called it a Massacre!

No mercy! No Respite!

Saint Mina of Ophelia VII of Order of the Bloody Rose of Orders Militant of Adepta Sororitas

Load up a transport with as few as troops as you can (1) and send it along with the normal fully stocked ones to invade your chosen planet. Once there use the one with very few troops to massdrive the planet. With that few a troops it will noy cause any damage and will wipe out a lot of the defending troops. Then send in your other transports ensuring they are in a fleet for maximum chance of success.

Works pretty much every time for me.

Using an effective but highly damaging invasion tactic with the number of troops limited so that it's guaranteed to fail but also guaranteed to soften up the planet for the "real" invasion *is* totally sensible. Back when I did invade planets I'd then follow up with mini-soldiers to actually take the planet with no permanent damage.

...Planetary Invasion, which requires a hell of a lot of beakers.  This pretty much eliminates the possibility of an early REX war in the game.

  (DA:)

  Use the "creativity" ability,  which increases the chances of receiving random free research time ("groundbreaking discoveries").  Early in the game with the lower cost techs,  this can complete much while your research output is low.  Don't rely on it - it is random!

  You can (errr,  in tiny galaxies anyway) wipe out the enemy,  then deploy ships at each of their planets and put 100% into researching planetary invasion.  Meanwhile you have increased the chance of their surrendering,  and your diplomatic power if you want to negotiate a peace treaty.

the bigger question is whether it's an exploit

  (realism of planetary bombardment):  perhaps the bombardment is a tech which targets enemy soldiers (who absorb the impact) and only destroys parts of the planet when there are no more enemy soldiers;  no-one has invented a way of switching it off once it has been started?

Creativity is one of the attributes you can spend customization points on (only one option - 1 customization point for a +25 bonus), which gives you a very small chance of completing research on your current tech whenever you hit the 'turn' button. Some races (Arceans for example) have unique techs that give you a creativity bonus as well.

Also, I would classify planetary invasion as more mid than high tech-tree. Are you playing with a slower research rate setting, or are you playing on a very small map? I usually play large/huge maps and research planetary invasion mid-game (when I have around 10 colonies, a few of the smaller ones dedicated exclusively to research) and I can learn the tech in about 3 turns even without triggering the creativity ability.

I have been playing with everything on random except for tech speed which I set to medium and I have tried sizes from 3x3 to 22x22 so far (not sure what the max is, my manual seems to think its 18x18 ) .  I've got PI down to about 15 turns before, by which stage I have usually filled out a lot of the shorter tech tree branches and have made good inroads into the others.  But then I always win the game before I can get any further, so I haven't really tried PI yet.  I assume at higher difficulty levels the AI doesn't just sit back and let you win Ascension like they have for me so far