Advice? Play something else.
Yeah. Not very good.
The graphics are alright, and it kills some time, but there are plenty of similar games. For example, Battle Gear (also by belugerin) is basically the same game.
However, in Battle Gear, the base defenses do not have to be activated manualy.
And you can order your troops to retreat or hold the line and not, you know, rush to their death like lemmings.
And the flamethrowers (at least, alien flamethrowers) do not magically burn units behind them, causing you to lose half of your units and prolonging the battle. That is very annoying.
Oh, and it is sightly more difficult to win a battle by pushing hotkeys at random as I just did.
So yeah. It is basically a weaker copy of Battle Gear with an annoying interface and magical alien flamethrowers.
And, of course, aliens.