I'm trying to get this handgun I read about online, but I think it might be a fake cheat; "What you do to get a USEABLE shot gun Which means you can use it and kill randoms on the street if you really feel like it 
. When your remembering your past on the milatary base when you have to save your brothes friends from the burning building you go to the Far right bunker in the sector that has the burning bunker in it go around the far right bunker and there will be a small hole with leaves on it near the entrance. Hold X and A and walk towards the hole untill you morph into the building once inside take the elevator down to the basement floor. Go to the Janitor closet which you can find on the map near the elevator door. Once in the Janitor Closet you will see a small box open this box and a key will fall down pick it up and leave this building. Now go to the Bunker thats closest to your house find the hole on the back side and once again hold X and A and walk in. Once in you will see a shotgun in a LOCKED case. Go use the key on the case and you will get 50 Bonus Points AND a shotgun to use throughout the game.
NOTE: You will find the shotgun inside your laundry room at your house untill the cops come and search it. After this you will always have the shotgun on you so if you dont like holding bulky shotguns everywhere then do not do this."
(from http://www.gamesradar.com/cheats/xbox/indigo-prophecy/)
. When your remembering your past on the milatary base when you have to save your brothes friends from the burning building you go to the Far right bunker in the sector that has the burning bunker in it go around the far right bunker and there will be a small hole with leaves on it near the entrance. Hold X and A and walk towards the hole untill you morph into the building once inside take the elevator down to the basement floor. Go to the Janitor closet which you can find on the map near the elevator door. Once in the Janitor Closet you will see a small box open this box and a key will fall down pick it up and leave this building. Now go to the Bunker thats closest to your house find the hole on the back side and once again hold X and A and walk in. Once in you will see a shotgun in a LOCKED case. Go use the key on the case and you will get 50 Bonus Points AND a shotgun to use throughout the game.NOTE: You will find the shotgun inside your laundry room at your house untill the cops come and search it. After this you will always have the shotgun on you so if you dont like holding bulky shotguns everywhere then do not do this."
(from http://www.gamesradar.com/cheats/xbox/indigo-prophecy/)