Once you enter a node you clear the purple 'infected' nodes by playing through them. The difficulty levels are easy, medium, and hard - and at times only the hard levels are available for an active node (large bright green spot).
After you select a node and start playing there are five minutes in which you have to take over the enemy base. If you run out of time or are unsuccessful there are 5 lives you can use, and you may also change to a different node.
I tried various nodes and found all the levels looked similar. Shooting at the enemies and their base did make for a sore thumb, but there is a pause option available to stop playing for a bit.
As you make your way to the enemy base there are some sparkling white circles which you collect to power up your cards. Each card (of which there are 5 per game you can have) is assigned a number key to make it easy to use in the heat of the battle.
I also noticed there is a 3D Map online component to the game as well, which I didn't get a chance to look into since I don't have a webcam. It seems that you download and print out a key, then connect with a webcam and place the key picture for the webcam to view. If anyone tries that out let me know what that does.
Overall the game was fun, but gets repetitive after a while. The main appeal I suppose is that this is a community based game where you work together to clear the nodes and stop the Overtakers from infecting the internet. The hard levels seem to be a bit too hard, and make it obvious why those tend to be the last ones available to clear most nodes. Yet, it is very responsive and a fun little game to play to kill some time.