Pg16: "A thick gray line indicates that the connected planets are supplied by your team." Might want to make a parenthetical "see page X for Supply" here, or ditch the past tense and rewrite it to use capitalised "Supply" so that it's obvious that it's a game mechanic.
Actually that's something I have noticed, anything that's a game mechanic should only ever be used in the same tense if possible, or have a parenthetical reference to what it's really called. It also should be capitalised. It's not only a good hint for the player, but it makes sure that your translations are much more accurate since present/past and active/passive versions can be translated completely differently depending upon the language.
Also, in a similar vein there's a lot of erratic capitalisation of buildings and ships. "command station" rather then "Command Station", sometimes in the same paragraph they are written with different caps. Then later on there's "science labs and Advanced Research Stations", "Science Labs" should be capitalised if you're going to caps the other ones as well.
Pg18: "Each metal and crystal harvester will" should be "Each Metal Harvester and Crystal Harvester will", not to mention the sentence is vague. Something like "Each Metal Harvester will produce 12 metal per second, and each Crystal Harvester will produce 12 crystal per second." is much clearer.
Pg18: Under "manufacturies" you don't mention the two different types by name. Second paragraph, first sentence should be rewritten similarity to the harvester sentence above.
Pg18: "As long as the planet is supplied by your team, any science labs and Advanced Research Stations on the planet will automatically gather knowledge." comma in the middle isn't necessary. Science Labs should be title capped like the ARS. Also should be some sort of "planet has Supply" or similar back reference as previous.
"You can unlock units in almost any order you wish, allowing you to customize your civilization to suit your preferred play-style." again comma not necessary, though this really should in active voice too, which would make the comma make sense "You can unlock units in almost any order you wish, this allows you to customize your civilization to suit your preferred play-style." (Though really maybe it should be two sentences? Gah, this English stuff is annoying...
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Pg19: Energy: You can't seem to make up your mind as to whether it's an "Energy Reactor" or an "energy reactor" again here.
Also you're using title-cased-"Reactor" rather then "Energy Reactor" in places too.
Pg19: "Low-power mode" is this hyphenated or not? It's different in different places.
Pg21: AI Difficulty: It mentions AI7 as being the level the AI executes all tactics it knows, I thought there was one or two tactics changes that kicked in at AI8 though.
Pg21: Auto AI Progress: you may wish to mention what the default is. (1 point ever 30 minutes? I can't remember it's been so long since I looked at that tab.
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Pg23: Command Stations: some command stations actually consume crystal/metal rather then produce it.
Pg24: Bonus ships: should mention that all players in a multiplayer game get the same bonus ship when they capture an ARS.
Should also say something like "examples of bonus ship types with more unique abilities follow" or something, also might want to note something like "over XX different bonus ships" or something in there as well just so it seems like there's a lot more then two.
"Shield bearers", aren't these things force-field bearers now?
"Science Labs" should be capitalised in title case if ARS are going to be.
(Still more to come, and yes more picky then usual. It happens when you've just done the same thing to a work related way-too-many-pages document.
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