The following are known Action Replay Codes for Geist on Nintendo GameCube (GCN).

Master Code – Must Be On
57RC-NDEA-2MD82
NFRW-Y6YT-X8BD3

Infinite Health
WJ7F-K639-KVDYP
BNW6-UU7N-52JWE

Infinite Ammo
G1HK-50JK-AF9C3
RZ3K-VQKJ-J4BBC

Infinite Boost
ER1T-QQM8-VG9EJ
16MK-J9D9-NQD2M
VYK7-Y6DE-RFYHM

Infinite Time
RPD6-31ZN-Z2QC7
JFAU-Q37P-JP3BD
P7BM-7ZGC-7ZTBY