Money Penny gives you a pen grenade to use.

Mission 4: Underground Uprising

Disarm the bomb when the counter reaches 0:07 for a special message from R, Full health, and a Full armor power up.

Mission 6: Night Watch

Use your X-Ray Glasses to see through walls and other obstacles to get a jump on patrolling guards.

Mission 9: City of Walkways 1

If you get the grenade launcher off of the enemy guard outside of the Warehouse, hold on to it until you reach the descending elevater: you can fire it at this point and take down all of your assailants at once.

Look for an armor jacket under the stairwell as you pass the boxes that block your path.

Mission 10: City of Walkway II

A well thrown sticky grenade will eliminate the enemies on the second floor of the building, allowing you a much safer passage.

A massive attack helicopter is waiting to ambush you once you leave Storage Warehouse #2. Exit the building, and then double back inside and wait for the helicopter to pass you by.

Mission 12: Fallen Angel

You can shoot the security cameras in the hallways around the computer room to avoid detection. This will reduce the number of enemies that attack in the area.

Mission 14: Meltdowm

Close the valve wheel to avoid being hurt by the steamo escaping from the broken pipe. If you become disoriented, use the lighting system as your navigation tool. There are red and green warning lights inside the submarine interior. Follow the green lights to the reactor room. The red lights indicate a dead-end.