Hi. The FAQ says:
Q: Will it have any copy protection?
A:No. Unless you consider requiring a user account copy protection (which we do require as it’s necessary to allow users to be able to re-download the entire game and receive updates and support).
Does this mean everyone can create a FREE account and play without buying the game? But the small notes below said something about Steam and Steam does not allow sharing (playing at the same time). So does this mean if I want to play together with my brother at the same apartment we both need to buy the game? Or is it possible/allowed to let him use my copy to play with him or any guest together?