Ship Control section is too telegraphic. The later example helps, but since raising the ship control level is what we do to win, this should be very clear.
Are Alert cards the only way aliens appear? It should say so, somewhere; perhaps in the (nonexistant) overview section. After step 5 of alien actions it says "if the game asks...". Will the game ask in any way other than an Alert card? If not, it would be clearer to say if an Alert Card calls for...."
I assume the alien ranks are listed in order from lowest to highest, but it should explicitly say so.