I started single player last night. Didn't understand that monsters came out at night so I had to quickly build a fort out of dirt and block myself in, in pitch black with the sound of hissing and skeleton bones right outside my door (I made the mistake of opening a hole to see what it was, ow). Scared the crap out of me!
On the plus side, while I was in there I buried down to make a pretty sizeable basement. Now I have a furnace, wooden/brick/tile house with glass windows and everything
And have been uses torches to kill animals for meat, haha.