Welcome to the guide. This game is really old and I'm a little late to the party, but it is still a really fun game to play and I would love to help other players get this achievement or become a bit better at the game.

So to begin, against the hard, cheating AI, you have a few advantages:

1. You can pause the game at any time - to spend your budget if you forget, to have a look at planets and formulate a plan and to look at the AI's planets and trade routes.
This is really helpful because you can gauge how far along they are and if you use the spy card, you can pause the game and study their strategy a little closer.

2. The AI is pretty dumb when it comes to artefacts and diplomatic actions, and in this guide, we use that to our advantage.
This means that you can use the host senate card and host research centre card and the AI will not oppose you in any way because it isn't a 'direct' threat against them. Also when there are random events, you can easily win them if you wait for the AI to vote, then simply you wait until there is about 5 seconds left. Then you just use some negotiation cards to get ahead and you'll get the bonuses.

3. Normally you can move fleets into their territory and they won't do 'much' about it.
What I mean by this is, when moving fleets into enemy territory. The AI are slow to react, but eventually they normally send a few fleets to monitor the situation and ensure that they'll slow your ships down until reinforcements arrive.

4. You also get to choose the map and their race.
So you can choose a bad race for them and already have the advantage before the game even begins.

Lastly, I thought this achievement would be pretty difficult, but I got it on my first run and pretty much an hour and half into the game. I thought I would have to set them back a bit more, but when the AI's points got to about 2200, they surrendered to me, ending the game.

So you want to start up a fresh game and choose the Mono race. After that, make sure you have only one opponent and that their difficulty is on hard, and all cheats are enabled (there should be a $ symbol and three +++ 's as well next to their difficulty).

Next, change the AI's race to Nyilli and set the map to 'The Expanse'. The one with all the remnants on it.

For this to be easy to do, you must ensure that remnant parts ARE enabled. These are very important for this strategy to work. This wouldn't work against real players, but as I said earlier. AI's are really dumb to diplomatic events.

If you want, you can increase the chance for anomalies and that will make it a little easier to get some extra energy or FTL generation early on.

That's about it for the setup.

Notes:
The Mono do not grow their population independently, they must build them. This aspect of the race slows the game down significantly at the beginning but doesn't really matter later on. This may be scary for players who don't play this race, but the ability to instantly transport colonist's using FTL and the ability to terraform planets is very useful. Did I mention they don't require food or water. All I see are advantages, now, terraforming was 'nerfed' but it is still overpowered. All they did was make textiles an extra $1M and double it after about 6-7 terraformed planets, but more of that later.

The AI's race the Nyilli do not colonise planets like other races, they build 'habitats' around them which act as population for the planet. This is a huge advantage for us because that means we don't have to capture planets and will save us a lot of time. Also they have things called motherships, which produce the habitats, If you destroy them, they can't repopulate at all and are basically wiped out.

Now if you have a basic knowledge of the game, you should be fine. But if you're a complete novice at the game check this guide out:
https://forum.quartertothree.com/t/star-ruler-2-a-beginners-attempt-to-conquer-the-galaxy/125503/46
When I first started learning the ropes, this was a really good guide to get around economy and colonising planets. You know the basics. But if you are familiar with the game don't worry about it.


So when you start off the game, immediately colonise the iron planet in your starting system, and invest all of your budget into population. Next, send one of your scouts to explore the system closest to the middle of the map, and send the other one around the systems next to your home one. Start your basic growth and colonise a tier 1 planet to make your home planet level 2. Then colonise a couple more tier 1 planets and a tier 2 planet to get the home planet to level 3. Continue this growth until your planet hits level 5. When colonising planets, aim for planets that generate money, influence and energy. You don't want any research or defence planets in this run.

While you are working on that, send that scout near the middle to all the systems bordering the really big system in the middle. You are looking for the revenant pieces. Be careful of Remnant fleets, but if your scout dies (which happens a lot if you move away to manage other stuff). Don't stress, just build a new one. Your main objective is to find all the remnant pieces. This is why we chose 'The Expanse' because all the revenant pieces always generate in those specific systems around the middle one. When you've found them all, sit your scout outside one of the systems and move back to your planets.

IMPORTANT
While all this expansion and scouting is happening, be on the constant lookout for 'Claim Artefact' cards in the diplomacy screen. They're instrumental for this run to work.

So now you should be at about the 30 min, maybe 45 min depending on your pace. You should be getting a steady income of at least $1M. What you want to do, is to start making another level 5 planet and terraforming a planet or too each income cycle. You want to alternate between making plastics planets and natural gas planets as they produce influence and energy respectively. Depending on your luck you should have around 8-16 influence, if you have been lucky, and have been able to purchase some 'Claim Artefact' cards. Use them. Just move your scout into the system to get vision of the revenant piece and use the claim artefact card on it.

It takes 4 influence and the AI won't take notice. Just wait for the timer to tick down and then boom. The revenant piece is in one of your systems. When claiming the artefacts, as a precaution, claim the ones closest to where the AI will go in order to get to the middle, because they'll start expanding towards the middle at around the 1hr mark.

When possible use the energy to activate the revenant pieces and you are almost finished. While you are waiting for claim artefact cards, keep expanding and terraforming to make more money, influence and energy. if you are lacking a quick energy generation, build a few solar generators in a few of your systems to generate a bit more energy.

Rinse and repeat all the strategies above, until you have claimed all the artefacts, keep saving up energy until you have activated them all. When you have activated them all, it will spawn the revenant ship, which has a strength of 50.4M, 1.6G of supplies and 2.7M health. Basically unstoppable. Use a telescope artefact or a spy diplomacy card to find the opponents homeworld and shipyards and send the revenant there. It is pretty fast so it won't take too long. Once you are at the homeworld (or the planet that has the most habitats). Head into the diplomacy screen and declare war on the AI. What will follow is complete annihilation. The revenant will decimate all the habitats and the AI will send majority of the fleets to "try" and stop you, but just target them instead and they will explode in a few seconds.

Keep travelling to all the different systems and keep destroying habitats. The more populated systems will have shipyards and motherships in them. Destroy them too, as destroying the motherships basically cripples their economy and labour production. Since the AI's race doesn't populate the planets, you can just destroy all the habitats and move on without needing to capture the planets.

Soon you will have taken out enough habitats for them to surrender and you will have beaten the AI, on hard difficulty and will all the cheats. This particular strategy could be classified as "cheesing" but it's an easy and efficient way to get the achievement.

A quick rundown of the guide is:
1. Slowly colonise as the Mono to build a steady income of: money, influence and energy
2. Buy 'claim artefact' cards whenever possible until you have 4
3. Use scouts to find all the Revenant pieces on 'The Expanse' map (They are in the systems bordering the big one in the centre)
4. Claim them, and activate them to get the revenant
4.5 Keep terraforming and colonising planets to get a good income of energy to activate the revenant pieces. Also build a couple solar generators too.
5. When the revenant is activated, send it to the AI's most populated system
6. Declare war and keeping annihilating the AI's habitats and fleets until they surrender.

In conclusion, this method is quite easy and the only factors that affect it, is a bit of luck for the claim artefact cards and the tier 1 and tier 2 resources. But all that affects is how long it will take.