A very good game all things considered. It would be nice if there were some more unit customization. Though Moon base + flamethrower + clones = pretty much assures you won't ever need to spend cash on troops again. A second one would definitely be appreciated.
Simply put D-day is the largest scale real life 'invasion' that people could wrap their heads around realistically. Didn't need an explanation in my eyes. It's not like the game is 'Gas the Jews'.
Way too easy. Just UP your luck and item spam using the Life form (collecting focus drops as needed). When you get down to the last two or three slow guys throw on the shock form with magnet.
The Untouchable ranks are pretty easy to get over the course of maybe 2 advancements. Just put on a pair of rapid fire weapons (beam cannon and gattling) then stay about 1400m away from small ships. They'll fire missles and you can shoot them down with plenty of room.
Begins to get mind numbing around level 15-20 (I had to stop at lvl 23). It would be loads better if there was some auto-equip function. Gonna have to grind it out to get the Impossible achievement.
All in all a good game. You can go a couple of routes, though I found that other stats really didn't matter all that much once I got some reproduction upgrades. Speed/agility is good for snagging early cells whereas str/def are a good combo for taking/keeping them.
If you haven't learned how the computer operates it sends out it's first RAEP-fleet at 50% HP, then the flagship about 10% HP left. Set it up so that you send a second fleet to hit just as your first fleet is destroyed, and they move out from behind the invincible base.