I found myself Googling How to get marker off of wood floor this afternoon because of this little guy.
And his masterpiece in the playroom:
If you notice, he tried to clean it himself with some toilet paper. I had a hard time scolding him because I thought it was pretty funny. But I used Woolite and then nail polish remover and scrubbed the heck out of it. I'd say it's 99% marker-free now.