KONAMI

Avoid Battle as Much as Possible

When you engage the enemy in battle, they will call for backup and try to take you down.
Even if you can take out multiple opponents, you'll likely suffer considerable damage in the process.
Try to avoid being spotted by enemies and use hiding spots to your advantage.

Sneak Behind Enemy Soldiers

Sneak behind enemies by making good use of radar, Corner View, and First Person View.

Let Enemy Soldiers Pass By

Find a place to hide from patrolling enemies and wait for them to pass by.

Treat Your Wounds

When you take damage, your Life Gauge will deplete and turn orange when it's low. If bleeding does not stop, your life will continue to decrease.
To stop the bleeding, use a bandage or stay still while in a crouching or crawling position.

Acquire Items

You can procure equipment and weapons to aid you on your sneaking mission on-site. Items are also hidden in lockers and under desks, so check anywhere that looks suspicious.
Switching to Corner View or First Person View may reveal hidden items.

Put Enemies to Sleep with the Tranquilizer Gun

You can obtain a tranquilizer gun and use it to put enemies to sleep during the game.
Doing so will allow you to proceed ahead while avoiding combat.
Enemies will fall asleep faster if you hit their head or heart. Use First Person View to aim for these vital points.
The number of marks above the enemy's head will decrease over time. The enemy will wake up when no marks remain.

• By using the tranquilizer gun, you can clear the game without killing a single enemy, including bosses.