4X space empire building strategy game. There are planets (obvious :D) How to make them interesting/unique/fun?

Bonus points if the complexity of the idea is kept at a reasonably low level :)

I don't really play 4X games, so take my ideas with a pinch of salt. ^^;

That said, a few thoughts (intended to be each individual suggestions, rather than taken all together):

• Randomly generate information and factoids for each new planet, giving the player something amusing to read.
• Have conquest of each planet take place via a simple, one-screen, fairly quick-to-play tactical engagement. For example, you might be presented with a planetary map divided into hexes, each representing a type of terrain: grassland, city, mountain, ocean, etc. You are then given access to a certain number of drop pods, a menu of units from which you fill those drop pods, and are then allowed to select the landing hexes for the pods (perhaps excluding cities). One your pods are down, your units automatically disembark, and enemy troops make themselves known. You then play out a simple tactics game against the enemy forces until one or the other side has no more units.
• Have each planet produce a unique unit, perhaps based primarily on the local dominant species but also somewhat randomly picked: for example, if planets A and B are both home to an insectoid species, A might produce a footsoldier unit that is similar to the usual insectoid footsoldier, but that moves faster than normal, while B produces a footsoldier unit that has an attack usually found on the insectoid flying unit, or a unit from another species.
• Have conquered planets occasionally spawn rebellions; this can potentially be dealt with by monitoring owned planets and managing a simple list of desires and concerns; for additional uniqueness, determine the list of priorities randomly for each planet: have a large list of potential priorities, then randomly pick a small subset for each planet. (Thus planet A might be concerned about tax rates, nearby battles and political freedom, planet B about numbers of troops drafted from them and resources tithed, etc.)

one word unicron

Other ideas:

Strategic resource - Have a collection of different strategic resources and planets may have at most 1 of these resources. They could unlock unique tech, or provide special bonuses. Every dilithium planet in your empire could increase fleet speeds by 1 for instance.

Culture - Groups of planets and races develop cultures over time. Those might provide bonuses and penalties depending on the culture and how your empire treats different cultures.

Specialized worlds, How about a farm planet? Or a Library Planet, or a single city planet, an entrainment world, or once made entirely of metal populated by robots, or a desert planet with giant sand worms.

- Forerunner Tech

Procedurally generate the remnants of an ancient space empire that spanned your local sector of space. Player may spent some portion of their resources on archaeology, which can (on a small and randomly selected set of planets) give access to ancient artefacts and technologies.

How about something similar to the book Solaris? A planet made of a sentient ocean. Throw in a dash of Lovecraft and you've got yourself a planet that terraforms you back. With tentacles. Gameplay wise it could be more a "Yup -- tried living there, the planet tried to kill us. Move on!"

http://en.wikipedia.org/wiki/Solaris_%28novel%29

How to make them interesting/unique/fun?

A single drop of water in a desert is interesting and unique, but quite mundane in a tropcial region.

The concept of interest/unique is similar to the concept of contrast. To create something unique and interesting you need to create something mundane first.

Well, what are mundane planets ? Are there terra-formed earthlike planets, populated planets, desert like planets, alien planets, water planets etc. ?

A very hi-contrast will make planets like bonfires. Eg. if most of your planets are desert like, with small colonies or even only a space station, then a tropical planet inhabited by aliens will be like a bacon the player want to explore. On the other hand, if most planets are terra-formed, containing some kind of wildlife, then a alien populated planet has not such a strong attraction and uniqueness.

Fauna & flora - alien animals and plants, some are simply a danger, some are a resource (drugs, vaccines) and some are disease carriers.

Radiation and other annomalies (groups of planets) - affects several planets (proximity), like a nova or "background space radiation" that affects all planets in that sector

or a desert planet with giant sand worms.

and with a strange substance that extends consciousness and allows folding space :D Sorry, couldn't resist :D

I am not much into 4X games either but,

I had found "rare galactic formations" at Spore quite fascinating, so if I were you I'd more think of stuff like symbiosis planets (obviously one's actions affect other) , twin suns, gas giants, wormholes etc.

Spore videos might easily reveal more. Also might incorporate basic laws of physics (like gravitation, fact that it was taking more and more time to go to center of universe at Spore was a good detail)

I would start with a system that generates believable systems, something like accretion will give you large numbers of believeable solar systemss.

Then seed the universe with your own hand generated systems on top.

Coming up with a system that generates believable and interesting systems is probably impossible.

Making up interesting planets just requires the correct amount of insperation, persperation, and stimulants.

The crystal planet from Starflight could make a cameo appearance, or a planet so dazzlingly beautiful the net effect of tourism forced the planetary government to introduce a law saying the net imbalance between what you eat and what you excrete is surgically removed from your body when leaving the planet. (Always get a receipt when going to the toilet!)

And of course the Big Bang Burger Bar, Eroticon 6, The Total Perspective Vortex, or a planet littered with dead whales and potted plants.

{How many of the references do you get }

and with a strange substance that extends consciousness and allows folding space Sorry, couldn't resist

Speaking of which... I wish someone would make a new Dune game. I played that 90's version like crazy.

[attachment=22799:DuneRTS001.jpg]

How about changing the color scheme, music, and over "tone" on the different planets? I remember playing Diablo 2 and getting to that desert chapter that had bright ambient lighting and psuedo middle-eastern music. It was such a refreshing change from the rainy fantasy forest of the first part.

It would help make the feel unique, I think.