In setup I see it says to put your alien race card facedown. It doesn't say anywhere (that I saw) to turn the card faceup. Did I miss something?

EvilAmarant7x said:

If you're playing a standard game, then everyone gets to see what alien the others are playing. Their intent by you initially placing your alien card facedown is so that other players cannot choose their alien based on what others pick (otherwise there can be some potentially lethal combinations).

So it's just a courtesy to make sure each player chooses their alien power independent of others' choices. Once everyone's decided, you flip them face-up and go.

...of course, as Jack and The Dukester will point out, there is a variant which keeps your power hidden until you decide to use it for the first time.

I'd probably be more inclined to say "keep THEM facedown until you use them" since we played with 2 powers per player, kept hidden. But Zach is correct about everything else he says above.