Hello witktom,
Thank you for your questions!
With a Hamachi network computers are added to a network and would then be able to communicate with each other. A computer's online/offline status will not effect weather it is added to a network still. In other words, if you need 10 computers on a single Hamachi network, you would need a Hamachi Standard subscription assigned to that network, regardless of if they are showing as online or offline.
Like pz said, Hamachi free accommodates up to 5 computers on a single network, adding a Hamachi Standard subscription to a network would allow you anywhere from 0-32 computers on that same network.
I hope this helps.
Regards,
Erik Elsom-Van Vogt
Customer Support Representative
LogMeIn, Inc.