Instant death in its various forms is a divisive topic in the gaming community. Their inclusion may create frustration for players, particularly when it isn't clear how to avoid the situation.
Common Types of Instant Death
A common form of environmental instant death is the bottomless pit, this is frequently found in 2D platformers. If players don't perform a successful jump, they will end up falling into the pit. Depending on the game, players may be returned to the previous platform, a checkpoint, or the start of the level.
Other forms of environmental instant death include spikes, lava, water, crushing traps, and fire.
For most of the game, players will lose only a fraction of their health when hit, until they encounter an enemy with the ability to kill them with a single shot or strike.
Scripted Instant Death
In recent years, instant death has also come to designate a type of message sending employed by developers to keep the player on a certain track.
With the advent of tightly scripted games aiming for a cinematic feel, developers have extra incentive to keep the player on a specific path.
The illusion of a cause-effect relation between the player's actions and the scripted animations triggered on his path is harder to maintain if the player is given a lot of leverage in the way he approaches the mission presented to him.
For the game maker, a radical way of avoiding this problem is simply to kill the player character upon venturing away from the intended course.
Scripted instant death has been criticized for providing developers with an easy way out of level design issues at the expense of the game's logic, as well as well as being unfair to players who favor a more deliberate playstyle.
For example, in Call of Duty: Modern Warfare 2, if the player tries to cross the first bridge encountered in the campaign on foot, Private Joseph Allen falls victim to instant death before receiving the following suggestion: "It would be safer to ride in the convoy".
This seems to imply that proceeding through the level on foot is more dangerous, but not impossible. In actuality, any and all attempts to move forward without climbing in a vehicle first will result in the player being sniped by an unseen enemy at the exact same point.
In all likelihood, the goal is just to prevent the player from bypassing the heavily scripted on-rail gunfight that ensues when the convoy enters the city.
Battlefield Bad Company 2 also adopted the "scripted instant death" mechanic despite freedom of movement being a series trademark in earlier installments.