Death Island

After signing up for a chance to go on a 1 week retreat to a deserted island for a tv show, you got accepted and went onto the island. You didn't read too much into the waiver you signed, thinking it was just a formality before the trip.You met 19 other people and then you hear sirens blazing.
"This is not a game, this is not a retreat. You are here on death island to kill, the last one standing will win half a million dollars. You have one week, this is a battle to the death and the killing starts tomorrow. Good luck." The sirens cut off.
The boats pull away off the island coast as people run in all different directions, who will survive and how will you win? What risk are you willing to take? How far are you willing to go... for half a million dollars?
Update: I don't feel like finishing this because I've lost all motivation so here.