About
To answer your first question, YES THIS GAME IS FREE :D !

Goal:
You will fight with ALL the players together against the (computer) robots.
You will need to kill the robots within the time limit or else they will invade the humans.
Attacking them gives you a advantage: You strike first, so it's easier to kill them by attacking them than by waiting for their invasion....
Although you CAN wait, since then your turrets, railgun bunkers and energy shields can take alot of damage too....

It's your choice:
-Will you build alot tanks/robots and attack the enemy, and kill them before they invade you ? (Attack)
-Will you build alot of missiles to kill enemy units without them harming you ? (Passive attack)
-Will you build alot of turrets energy shields etc. to blow away the robots ?


What will you be doing in Robot Revolutions ?
In Robot Revolutions you build, and research constructions. You need to build resource gathering buildings and alot of units to free the humans. The humans are surrounded by robot drone's and other terror war machines !
Also to keep the game fun, there are some random attacks of partolling robot groups now and then.


Others
Building and researching will cost some time; from 1 to 50 hours real time.
So you can start building today, sleep and use your new building tomorrow.
The advantage of Robot Revolution is that you do not need to play alot to become the best player.


Conclusion
I guess you've noticed this game is very unique, isn't it atleast worth a look ?