Have to agree with Catinthewall... the low cost to attack neutrals render all strategy moot... it's just a question of whether or not you can click faster then the AI is set to move.
Which is no fun.
Pretty easy... once you get laser towers, just max them out and surround them with a mix of other towers, and the combination provides enough status effects to stop and kill everything. Upgrade factories when you have free cash, and you shouldn't have any problems. There's a bug where lots of rockets going off (as a result of lasers making them fire) glitches the graphics by leaving lots of explosion marks everywhere. Other then that, pretty good; played endless until it was obvious I couldn't lose.
I seem to remember playing a game almost identical to this one... but it seemed much better for some reason. For one thing, there were prices on the weapons, so you could see what it was you were buying...