When you play in one player mode, you will get Serious Sam. After the first level loads and saves, exit. Go to one player mode and start a new game by pressing Y. A messed up name will appear. Do not delete that name; just select "Done". Allow the game to load and save, then exit and go to one player mode. If done correctly, Serious Sammy should be there. Keep doing these steps until you get all the charcaters. Note: When you get Serious Sam 2, do not select "OK"; there is no difference.