Sound Manipulation
Guards in Metal Gear 2 react to sound. Walking on metal grates or broken glass will alert nearby enemies. Conversely, you can use this to your advantage. Firing an unsuppressed weapon in one direction can draw a guard's attention, allowing you to sneak past them from another angle. Experiment with different surfaces and weapon types to understand their sound profiles. Crawling is always the quietest option.
Line of Sight Exploitation
Guards have a limited cone of vision. You can often walk directly behind them without being seen, even if they are very close. Use corners and doorways to break their line of sight. Remember that security cameras also have a fixed field of view; observe their patterns and move during their blind spots. The radar is your best friend for visualizing these sightlines.
Cardboard Box Tricks
The Cardboard Box isn't just for hiding. You can use it to travel on conveyor belts undetected. Some guards might also become curious and approach a stationary box; if you're quick, you can pop out and punch them before they raise an alarm. Experiment with placing the box in unusual locations to see how guards react.