There are also three Sniper Assassin levels, which play fairly different from the rest of the game as they are more arcade-like and see you fixed in place using a sniper rifle to eliminate several targets, and I'll get more into how these levels work when we come to them. This walkthrough is also written assuming that you're playing each DLC in the order they're presented here (with one exception at the end of Hawke's Bay where you are forced to unlock a Sniper Rifle elsewhere in the game) if you play the DLCs in a different order, it's likely that you'll lack an item or weapon that I tell you to bring.

This walkthrough will guide you through each of the game's levels to reach the ultimate goal of Mission Mastery Level 20 (or less on some of the smaller levels) in an efficient manner whilst earning the other achievements on the way. Every level has challenges that will give you XP and count towards your Mission Mastery level, and as this gets higher, you'll unlock new starting locations for that level and items that can be used elsewhere in the game, amongst other things.