1. Foreshadowing If the scenario where the stalking begins is not from the beginning of the game, use the PC's hero or character with god like insight or a team of more trained and more equipped characters telling the PC there's no hope.
2. Telepathic link or visions - overlay the monsters actions to the PC's screen in realtime on occasion - you never see the monster but you see it on a rampage or becoming aware of the PC's presence and evolve the stalking over time.
3. If your graphics team can do it dynamic and animated tonemapping/contrast/exposure/brightness for the monster. In this way the monster can be in the PC's FOV and the PC sort of know it or think they know its there. Exactly how to incorporate into game depends on map lighting conditions - is the visual of the monster something akin to the predator in the movie or does this partial visibility only happen in the dark i.e. shadows, nighttime, or large dark areas.
4. Loss of control - if the PC's personality is from a certain set you could justify a loss of control (can't run as fast...) or change in control system such that the only real option for the player would be to run because an inability to defend one's self easily.
5. If the monster eats it's victims loud "eating" type sounds might be nice.
Thats all that I could think of off the top of my head.
edit - 4. Loss of control - if the PC's personality is from a certain set you could justify a loss of control (can't run as fast...) or change in control system such that the only real option for the player would be to run/hide because an inability to defend one's self easily.
3. If your graphics team can do it dynamic and animated tonemapping/contrast/exposure/brightness for the monster. In this way the monster can be in the Players FOV and the Player sort of knows it or think they know its there. Exactly how to incorporate into game depends on map lighting conditions - is the visual of the monster something akin to the predator in the movie or does this partial visibility only happen in the dark i.e. shadows, nighttime, or large dark areas.