From The TimeSplitters Wiki

Dusk of the Dead
IMAGE NEEDED
Game	TS1
Section	1
Map	Mansion
Character	Det. Harry Tipper
Enemies Encountered	Brown Zombie Girl Zombie Green Zombie Jacket Zombie Police Zombie Skull Zombie
Rewards	Jacket Zombie Police Zombie Skull Zombie
Medal Requirements	10000 points

Dusk of the Dead is a TimeSplitters 1 Challenge. It involves shooting the heads off Zombies in Mansion.

Briefing

As the sun goes down, the ghouls come out. Make your last stand in the mansion front hall. Who knows, if you score 10000 points you might survive to see the dawn.

Strategy

Keep in mind this strategy doesn't help much. Start at the bottom and use your radar to see where the closest zombies are and shoot them. Easy, right?

The first few are simple, however, they'll be more zombies later. Start off normally, and when there are too much escape to the top. Look left and right down the corridors and shoot the zombies at top and and zombies that have managed their way up the stairs. Most won't, and that's what makes this strategy work. If you stand at central top, after all the zombies have spawned, look through the banisters and shoot the zombie's heads off from up top, they'll just be walking round in circles down below. When you've killed all the ones easy to shoot. Run down and kill the last few if there are still more. Pick up the guns and get ready for the next wave.

This strategy only got the writer a small victory after several attempts. Hope you're better?