Planet finding is almost luck...One game I chose Ice/None, there were three huge Ice/None in my home system, all with moons, a few of them even Ice!!. I honestly don't know if if depends on the system chosen though, I usually go for spiral, and my other (rare) choice is cluster. I've been playing Rock/None on average almost every game since I started playing back in October, but lately I have been picking other combos just to see what it is like.
And yes, sometimes having the atmosphere/planet type no-one has is THE edge in the game, like Pukes Junkyard game, I believe everyone mostly chose rock, a few chose Ice but I think only one chose gas. It is set on only colonize own planet/atmosphere, That 'gas guy' has a huge advantage, esp since EVERY planet has tech left behind to discover, and NO research is allowed.....but as usual, I digress....
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"And what the hell would you know about sanity?" demanded Beatrice. "There are depressed lemmings on the edge of cliffs who've got a better grasp on reality than you have. And more common sense."--Simon R. Green 'Deathstalker Rebellion'.
"We are all...the sum of our scars"....(paraphrased) Matt. R. Stover-'Blade of Tyshalle'.