how can I play offline?

You need to be offline, that's all. Can you please post the full log?

Where do you get the text that is in your opening post? It's not contained in the logs?

You can either turn Steam to offline mode or remove your internet connection.

Originally posted by Lord Autismo:

Originally posted by SLG-Dennis: You can either turn Steam to offline mode or remove your internet connection.

How is this considered an acceptable soultion, when offline play already existed before being taken away from us without workarounds

Offline play is solely intended for when someone is actually offline or the backend servers are - then it will also go into offline mode, this will include issues with backend servers when they are online as well in the near future. Offline mode is not supposed to be used for any other purposes (including manually turning servers into offline mode despite being online), hence the solution as implemented achieves the intended goals.

Originally posted by Marco croto: It don't tell me how to it ;)

Is it possible to play offline ??
Seem to be since new update but for me nothing worked

I've already informed my colleagues and will let you know when they had a look at your logfiles. So far offline mode seems to generally work when done correctly (both client and server need to be in offline mode), so it may take a bit for them to check what the exact problem is here.

If you are offline, it will automatically do that, otherwise adding -offline to the commandline will do so.