There is no real exploit glitch you can take advantage of. There are a few missions that are very difficult to S rank. Firefly and Operation Ascend are among the very hardest. Despised Icon has very good builds in his guide and will take you 95% of the way to 1000 with very little time investment and only some skill.
Sorry I have never played Prototype so I can't give you any comparison to it. This shooter is very different to other shooters because you will be flying and there are 5 attack buttons. The controlls are a bit awkward and you should probably modify the layout to be condusive to you.
There are some members who still frequent this forum if you need help. Just PM and/or post depending on the issue.
Last edited by Shinobi273; 02-20-2012 at 06:12 PM.