Easiest 1000g Ever!
Took me 2-3 hours to complete standard campaign and unlocked 700g in this time. Then took me 2 hours complete the game on Veteran mode and get my achievements to 970G. I didn't bother with the collectables for 30G.
Tips for Veteran mode and making the game easier. When you get armoury points, unlock the weapons first. They make the biggest difference to the games difficulty factor. If you selected health packs, ammo or grenades first, press X to reset, your campaign progress will stay the same.
The shotgun allows you to take multiple enemies out with one shot. The chain gun however is my favourite as it's turn speed is so fast, you can literally take out a screen full of enemies in a second. There's 80 bullets to a magazine as well so just spew them out.
Also this is just my impression but the hardest part of the game is levels 1 and 2 because there is a learning curve and these levels have some really challenging parts. Once you get to level 3 and beyond, it's all down hill.
The achievements literally take no skill and you'll be rolling them out, wondering how you even got them. Whether you are a Time Crisis fan or Call of Duty, this is game deserves to be played. I guarantee you will enjoy it. There's no other game on the 360 in this genre.