Here's the game roughly explained:
Everyone tries to draw what the game master wrote on their cards, but are only allowed to draw one line each (If the topic is "cat", you could draw an ear or a whisker, so that the others know you know the topic).
There is one fake artist among the players who doesn't know the topic and draws a line randomly.
All players can draw two lines all in all and then have to decide who the fake artist is.
If the fake artist gets the most votes, he loses.
If he doesn't get the most votes, he and the game master win the game.
Now you might think it is extremely easy to find out who the fake artist is, but there is one more rule.
Even if the fake artist got the most votes, he can still guess the topic of the picture everyone drew and win if he guesses right.
Knowing this rule it becomes much more difficult for the real artists to draw their lines, because they want to show the other artists that they know the topic of the picture, but don't want to be too obvious in front of the fake artist.
...so the picture becomes a crazy mess!