Sometimes "level cheats" refer to the four-digit codes needed to open doors and progress. Here are a few critical ones for early levels in the first game: 091772 and 5929. CIA HQ: 7687, 110598, 2019, 110700, and 0614.
In the original trilogy, "Level Cheats" typically refer to hidden codes that allow you to skip missions or unlock every level from the start. These methods vary significantly depending on whether you are playing on a console (Xbox, PS2, GameCube) or PC. Quick Unlock Codes (Consoles) Splinter Cell Level Cheat
In the Solo/Co-op menu, hold the Left and Right Triggers , then press X five times and Y five times. Sometimes "level cheats" refer to the four-digit codes