Problem:
Back on Metro Prime - in the arcade I found it very difficult to win sufficient tokens to get a ticket to the zoo.

Solution:
Ask the attendant for some tokens & save the game Hack the save file with the highest number (e.g. save.027) and change the 1497th byte (hex 5D9) to 244 (hex F4) using a hex editor (such as Matt Dawson's FileView). You now have enough tokens to ask the attendant to let you play on the other machine upstairs.