I'm looking at the Humble Store and the puzzle game "Critical Mass" is listed there. It looks interesting, but I can't tell if it's truly DRM-free. In the game's description it says, "Critical Mass is available as DRM-free Offline mode only, please disconnect from the internet to enable the Offline Mode option."

So does that mean if the player is online they cannot play the game? Why do they have to "disconnect from the internet?" Does it need a client to run?

Bump.

It means they have some sort of drm in place for online play. So, if you want to go online to play with others, they'll do some sort of verification.

Does that answer your question?

But my question is, if a person only wants to play singleplayer, but also does not want to "disconnect from the internet," will the game still work?

I'm reading the same description you are, and of course the game will work, but it will not be drm-free unless it is in offline mode.

That's too bad that it isn't fully DRM-Free.