Enter 5SQQ-5THA-ZFFV-7XEV as a profile name. If you entered the code correctly, you will be able to re-enter an actual profile name after selecting Done. When you begin the first level, you will have the BFG weapon. Alternately, enter HQ6G-ZP3B-C5LE-WMXA or EG4P-ZGUJ-6SQJ-3X68 as a profile name. Make sure to include the - symbol when entering the code (located next to the ! symbol).