There are 2001 achievements to be had in this game all easy to get.

More easy guides here to get 100% here

Controls

W = Forward
A = Left
S = Backwards
D = Right
E = Interact
Tab = Map
Left mouse button = Fire
Mouse wheel = Cycle weapons

1) Load game select single player (image 1 below) then select campaign (image 2 below) then new campaign(image 3 below).


























































2) When you spawn (image 1 below) turn around and walk to the tall tapestry (image 2 below)
Walk up to the giant tapestry press E It will give you a riddle. Go to the location in image 3 on your map the take the flag image 4 below. Then turn around and go back to the tall tapestry (press E to interact). Then you get teleported.

1) You are spawned here image 1 below. Press escape button and purchase weapons + ammo image 2 below. Move forward and find the mystical lightning ball image 3 below it needs to be this one not the long thin one interact with it (E) enemies will spawn kill them pick up coins they drop (to buy new weapons) when they are all dead click the ball in image 3 again more spawns rinse and repeat touching the ball and killing enemies till all the achievements have popped. If you die (which you will) you have to start again taking to the tapestry then getting the flag again.