players can also build up a combo meter by killing mutants to receive a score, with further points gained by performing head shots, shooting bonus pickup, saving civilians and attaining multiple kills without missing a shot. if a player dies, points from his or her overall score can be spent to continue playing. at the end of each level, the player is awarded a grade that depends on his or her final score among other factors such as not dying, and accuracy of shots. along with score bonuses, other pick ups scattered throughout levels include health packs, grenades, the "slow mo-fo" pick up that puts everything into slow motion temporarily and the "evil eye" feature in which shooting a certain environmental point destroys any lurking mutants nearby.