Hidden bonuses: 7
Level walkthrough: Start running forward and turn right when you get to a collapsed section of the tunnel. Use you bionic arm to reach the warehouse which is located directly above your current position. Explore the warehouse to find the first bonus item and use one of the beams to go outside the building.
Notice that an enemy Polycraft has appeared above the warehouse. Use one of your primary weapons to destroy the machine, wait for the Polycraft to hover to perform several zip kicks or ignore it entirely for the time being.
Proceed to your right and use nearby pipes and other large structures to remain where it's safe. Notice that you'll be targeted by enemy snipers, so you shouldn't make any unnecessary stops along the way. The second bonus item will be floating in the air. You can try taking it right now or you can wait until you've eliminated all hostile units.
You'll soon notice that a new pod has landed in the area and it'll contain a sniper rifle. Take this weapon and spend some time eliminating enemy snipers. Once it's safe proceed towards a huge bridge.
There are new enemy guards standing next to the bridge, however I wouldn't recommend using the rifle to kill them, because you may need the bullets soon. Make a jump towards the bridge, kill all enemy units and proceed to a huge pillar with a number 2 painted on the side.
You shouldn't have any major problems reaching the top of the bridge as long as you're careful enough. Head forward and you'll soon find the third bonus item. Your current objective is located to your right. Head down there and approach the force field. It won't be a surprise that you're going to be attacked by new Biomechs.
Obviously you should rely mostly on the usual methods of defeating the mechs, however there's also a way to outsmart both machines. You would have to go back to the bridge and start aiming at the glowing spots on their armor. Either way both machines must be eliminated, because only then the force field will be disabled. Proceed towards a new warehouse.
Go to your right and get ready to defend yourself against a large group of enemy guards. They will appear once you're close enough to an upper platform and it would be a good idea to kill them without losing any ammunition. Once they're gone proceed to the designated area of the map and hack into a relay station.
Make a few steps forward and start using your bionic arm, grabbing mines as you progress. Ignore some of the nearby snipers and instead head on to a large blue cylinder located to your left. The fourth bonus item can be found on one of the balconies of the tank.
You must use a large beam to get to other cylinders seen in the distance. This of course means you'll have to use your hook and start swinging. Once you've landed on a new cylinder eliminate the nearest sniper quickly. Approach the pod and interact with it to collect a grenade launcher.
Notice that new Biomechs have appeared in the area. Defeating them is not going to be easy, because you'll have a lot of problems finding a stable platform from where you can start firing. Make sure to use a grenade launcher. You can also consider throwing bodies of fallen enemies at them, as well as perform adrenaline finishers.
The fifth bonus item can be found floating in the air and you should consider grabbing it once you've dealt with the mechs. I would also recommend securing a cylinder with a few guards standing on top of it. Keep heading towards your current destination. Eliminating the last sniper should allow you to gain access to a new building.
Proceed towards the exit. Turn around when you've arrived and use your bionic arm to get to the upper level. Explore a nearby roof section to find the sixth bonus item. You can now start moving towards the current checkpoint. Watch out for enemy units along the way, including new snipers.
You should be able to find a new pod in the area, however it contains a machine gun, so I would recommend ignoring it if you're carrying a grenade launcher or a rocket launcher. In order to get to the last seventh bonus item you must get to a large structure located to your right. You can reach that area easily using one of the balconies.
Make sure that you've been able to eliminate all enemy units and get to a large conveyor belt. Start moving forward. Thankfully you won't have to perform any additional jumps along the way. Just get to the exit and you'll be rewarded with a new cut-scene. Get ready for the final act of the game.