Killer7 Infinite Serum Vials in Killer 8 Mode: At the Press Start screen, press Down, R, Up, L, Y, B, X, A. You get 100 serum vials every time you begin the first level. Just keep re-entering the first level to get as much serum as you want. Game Mode Unlockables: Beat the game on Normal or Hard Killer8 Hard Mode + Young Harman playable character Beat Killer8 Mode Hopper7 Mode