First of all, this game looks to be AWESOME! This is the most complete alpha I've ever seen.
On that note; here's some ideas:
Since this is a online game, the game won't pause when you enter the menu screen. Could the background (the area behind the character and everywhere else be a bit transparent? So I can see if I'm about to be attacked.
The fireteams are a bit small, could that be upped to 5 or 6 players, or even more? Would be fun to be able to play with all my friends at the same time. Could you also make it so that if you enter orbit, while in a fire team, you don't auto leave the fireteam? That should only be done through a menu or something. So you know that you are about to leave the fireteam.
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I don't know if I would like the transparent background. Maybe there could be an option to adjust the opacity so everyone can have it the way they want. I like my solid background options menu.