To use a cheat code just type it in during the game

Result                  Code
----------------------------
Gain shovel bonus     - ADlsz 
Gain cage bonus       - ADlck 
Speed up              - ADufs 
First-aid set         - ADafa 
Life                  - ADjls 
Lighting              - ADmlb 
Invisibility          - ADnif 
Gain gun bonus        - ADpgr 
Fire shield           - ADofv 
Freezing              - ADzfh 
Key to the next level - ADkvk