The aliens never seem to attack your planets until very late in the game, after they have colonized a lot of the uncolonized planets in the universe. I can't guarantee that the aliens will attack late in the game but it is very likely that they will leave you alone until at least turn 150. As soon as possible, build an exploration ship and send it with a couple of other combat ships (for protection) to the surrounding planets, this serves two purposes; 1) to look for planets to colonize and 2) to look for alien life-forms.

When you find alien life-forms and the empire offers you fleet forces or resources (a transporter partially filled with food, material and energy), I would recommend that you always take the fleet forces because spaceships are usually much more useful than a transporter partially filled with food, material, and electricity. Also the empire can instantly send the spaceships to any planet which cuts down the time spent exploring the universe for good colonizable planets.

When the aliens attack your planets in overwhelming numbers and you do not have a realistic hope of recapturing it, it is most important to destroy the energy storage units so that when you come to destroy the planet with your planet destroyer and the aliens have built a planet shield, you can destroy the planet since you need twice as much energy as is contained in the planet's energy storage units (if you have demolished the energy storage units, that should be 20 energy units).

When you no longer have a use for the colony station on your colonized planets, it's a good idea to demolish them. This gives you 11 units of material, one more place to build things, and the you still have the space for 4000 people, that you had before you demolished it. The higher the difficulty level, the more objects the aliens tend to build on their planets. On the easy level they tend to build four objects. Typically:

1. an alien central unit
2. a nuclear power plant
3. a ground defense unit
4. a space port.

1. an alien central unit
2. 2 nuclear power plants
3. 2 planet defense units
4. a space port
5. 2 energy storage units
6. a planet shield
7. an anti spy satellite antenna

This gives the aliens a maximum of 620 units of energy and the alien central unit produces 24 units of material per turn regardless of which difficulty level you are playing on. Don't leave your spaceships in orbit around planets colonized by the aliens as they will build tripods (alien troops) endlessly until you leave which can cause problems later on if you decide to invade the planet with troops.

It is difficult to say how many planets should be colonized to their full capacity, as it largely depends on how quickly you defeat the aliens and the difficulty level you are playing at.

The best planets to colonize are planets with the highest food and mineral wealth (petrol and metals) though mineral wealth is more important since greenhouses can be built to provide food but mining sites cannot be built. There are two main ways to defeat the aliens:

1. invade their planets with spaceships and troops (very difficult and time consuming)
2. keep building spaceships, and research until you reach Technology level 9 and then build a planet destroyer and destroy all the planets, that the aliens have colonized, and then wipe out the aliens with your large fleet (much, much less difficult and much, much less time consuming).

It's best to choose which of these methods you are going to use near the start of the game (needless to say I would recommend the second method). If you choose the first method you will need to build barracks (one or two per planet should be enough) and troop transporters. If you intend invading the alien planets with troops, you'll need approximately three or four times as many troops as there are tripods defending.

If you choose the second method you will need to build lots of fusion power plants (six or seven), seven or more energy storage units and a planet destroyer on the same planet. It is best to build these units on the planet farthest away from where you think or know the aliens are, so that it takes more energy when you use the planet destroyer. That way if the aliens have a planet shield, you are more likely to destroy their planet. The most important part of this game is that you can only ever build thirty-five objects on a planet.

But remember you can bulldoze them for the return of half of the material it cost to build them. The bulldozer facility along with the increased number of different constructions gives the game a lot more flexibility. This means that the number and type of objects built on your planets will be different from game to game. Always remember to demolish constructions on your planets after they have ceased to be useful, especially irrigation units, snow melting units, and universities.

When Technology level 5 is reached you should build fusion power plants and demolish any energy collectors, coal power plants, and nuclear power plants. If you use method two, after you have destroyed all the alien's planets, the planet destroyer, extra fusion power plants and extra energy storage units can be demolished.

The mother ship is a very powerful spaceship and the only ship capable of repairing itself. Destroying it will stop the aliens colonizing other planets but they can still wipe you out with combat ships and troops. When you have built a planet scanner and think you have enough combat ships to protect your planets, try to find the mother ship by sending some fighters to all of the planets or you can just wait until it finds you, and then track it with the planet scanner and send enough ships to destroy it (12-15 pulsar destroyers (at Technology level 8 or above) or equivalent should be sufficient). You will have to chase the mother ship from planet to planet as it usually moves, once it has encountered resistance. Do not attack the mother ship with small numbers of ships as it will destroy them and by the time you have attacked it again it will have repaired itself.

Playing against a human opponent is more difficult than against the aliens. Humans can use energy cannon or a planet destroyer against you. The number and type of buildings built on your planets is roughly the same as against the aliens, but all of your planets should have universities, because being the first to develop an energy cannon or planet destroyer can accelerate victory. A planet shield is also advisable so that there's less chance of the above happening.

The planet scanner becomes a more useful piece of equipment. It can be used to discover which planets your opponent has colonized. Because from time to time, spacecraft will move between the planets and it is likely that the busiest planets will be colonized. It will at least tell you which area of the universe is being colonized or explored.

Building spy satellites is still a waste of time and resources as your opponent may have an anti spy satellite antenna and knowing what is happening on his/her planets is not a major advantage. You can only be 50% sure of the number of spaceships in orbit around the planet.

After the planet destroyer is used, it should self-destruct afterwards. If you have enough energy you can take two or three shots with one planet destroyer in the same turn by selecting the option more than once from the special commands menu.

If you use the planet editor it is worth knowing that when you design your own planet and come to save it and you use the 'GB' keymap you will need to press the 'Z' key instead of the 'Y' key, to save it.

On planets with few mining sites, greenhouses are best built on desert or ice terrain. But on planets with a lot of mining sites (more than can be mined by your intended population size), build them on mining sites since one shield of material is also gained.

These are best built on sites were metals or petrol are present. When enough food has been produced for the population and you have built all of the structures you require, use the remaining mining sites to build as many mining robots as possible.

Two energy storage units per planet is a good idea especially if you intend to to install a stargate ship when Technology Level 6 is reached. Because stargates now require energy to function. If you intend to build a planet scanner or energy cannon on the planet, two energy storage units is fine, but if a planet destroyer is built a minimum of three is needed to be able to fire from a reasonably long distance.

Ground defense units can be omitted since the aliens rarely if ever attack your planet with troops until many turns after they have captured it. If you do build ground defense units, they are very quickly destroyed if the aliens attack.

If you use method one, one or two barracks per planet is fine providing you have or intend to, colonize additional planets. This does not strain the resources of any one planets to much. If you use method two, barracks are obsolete.

Provides four units of energy. Only worth considering when you first colonize a planet and need more energy to build a city complex or you want to build a high energy consuming construction (such as a planet destroyer) and you do not have quite enough energy and you are sure that you won't need any more energy.

Provides eight units of energy. Only worth building if you have a small number of shields or you have not reached Technology level 5, after which you can then build fusion power plants.

Provides 16 units of energy. As soon as these become available and you need more energy to build one. Remember you can always demolish energy collectors, coal power plants, and nuclear power plants. This not only gives you more space on your planets, but more energy production as well.

These are only really useful when you have a planet with a lot of ice terrain. It would be best to colonize another planet, but if you do build one remember to demolish it after it has changed the ice into grassland.

These are only really useful when you have a planet with a lot of desert terrain. It would be best to colonize another planet. If you do build one remember to demolish it once it has changed the desert into grassland.

It takes four energy units, a long time to build and at least 700 energy units to fire, but it is very useful to destroy the alien planets, especially on the hard and suicide levels since it is difficult to destroy all of their vast numbers of spaceships. Destroying the alien planets stops them from producing spaceships and then you can build up a large fleet of combat spaceships and destroy them.

This device uses 20 energy units for a short range scan and 50 energy units for a long range scan. One per game is needed, which is best built on the most central planet in the universe, since with a long range scan the movements of the alien spaceships can be seen throughout most of the universe.

Stargate ships should be built at your earliest opportunity when Technology level 6 is reached. Stargates should be established at all of your colonized planets. The distance between stargates does not effect the amount of energy needed to make the jump. The amount of energy needed to make a stargate jump with each of the different spaceships can be seen below:

The best use for the transporter is to move between all of your planets, loading and unloading food, material and energy as needed. It is especially useful for collecting energy for a planet destroyer attack.

Build an exploration ship as soon as possible after Tech. level 2 is reached and send it out with a couple of combat ships as backup to explore planets for alien life forms and colonizable planets.

Fighters are only really worth building to protect exploration ships and to explore the universe early on in the game for good colonizable planets. It is difficult to say which combat ships are the best to build. Dreadnoughts take less time and material to build and aren't that powerful. Cobra Ships take more time and material to build but are more powerful. I find that Pulsar Destroyers and battlestars are best to build as they are very powerful and give you more time to get reinforcements to a battle.