Zapping is a gameplay mechanic in Resident Evil 2 which allows the player in their first run to affect how things play out in their second. The concept emerged late in development of Resident Evil, and was reconsidered when production on Resident Evil 2 was restarted in Spring 1997.[citation needed]
The zapping system only appears once the game is replayed with a different character; the player's actions in Leon A will affect the game's events in Claire B. Likewise, the player's actions in Claire A will affect Leon B. There are a total of nine "zapping" instances in the game:[1]
If Brad Vickers is unlocked in A, he will appear in B, even if he was killed in A.
If Marvin Branagh is killed in A, he will not show up in B. If spared in A, he will appear in B.
Taking the SMG and/or Side Pack in A will make it not show up in B.
If the cord was used in one of the hallways in A, it will remain safe in A, but zombies will eventually break through the windows in B. If the cord was not used in A, then both hallways will become dangerous earlier in B.
If the Alligator was not killed in A, it will return in B.
If the vines in Sleeping Quarters A were not burned out in A, they will appear in B.
If the B.O.W. gas in NEST was turned on in A, enemies will become weaker in A only. In B, Plant 43 will become poisonous due to the prolonged exposure to the gas. If the gas was not turned on in A, Plant 43 will not be poisonous in B.