Woo Hoo - I HAVE WON!!!
I tried and tried and tried again, and I have finally won this game!
The trick is, all of the Bandits start out in one place. If you move to a certain spot, they seem to move forward a bit in one direction, or turn and move. You just have to find their spots, and figure out their plan.
A hint I offer is that if you can see them, and there are no objects between you and the bandit, and if you are far enough away, the bandits might not be able to see you - so shoot them! It's all a matter of sneaking up on the bandits. For all 15 bandits, I figured out the position of where I should stand, and where I was still too far away from the bandits for them to notice me, and I took them out.
There is order involved too. You should take them in a certain order. Here is the order I used. The blue dots show where I stood to get the best shot:
The bandit #15 in my map above cannot be shot from the south. He must be shot from the east or from the west.
#14 must come out first before you can shoot him. Start walking up to him, and when he comes out, walk back far away and shoot.
It was indeed a great game! I even found the secret!