Casual beat by myself
Hardcore mostly by myself (the some co-op)
Insane via Co-Op (just got annoying CONSTANTLY restarting a whole area when you die)
The hardest part on insane was the end. Seriosly, we did it like 40 times to try and beat RAAM. It was wierd to cause there were a few times when i perfect reloaded everytime with the sniper and felt like i just unloaded like crazy on him, yet he did not die. Then the time that we did defeat him it seemed like we shot him about 1/2 as much.
Another difficult part on insane was the car, we redid that part about 20 times
