In video games, a scripted sequence is a pre-defined series of events that occur when triggered by player location or actions that play out in the games engine.
Some scripted sequences are used to play short cut scenes that the player has little control of. However, they are commonly used in games such as Half-Life or Call of Duty to bring in new enemies or challenges to the player in a seemingly surprising manner while they are still playing. They can also present further plot points without requiring the player to take a break by watching a cut scene. The intended results of this style of presentation is to increase immersion and to maintain a smoothly-flowing experience that keeps the player's interest.
Scripted sequences trigger off of a number of things. A timer, progress of the game, or a check point could activate a scripted sequence. For players that speedrun video games, skipping these scripted sequences that would otherwise slow down their completion time is a talent. Being able to manipulate the games hit boxes so that the game does not trigger sequence is efficient for fast completions.
Half-Life uses scripted sequences throughout the whole game. Walking near other characters can trigger scripted sequence of dialog. These dialog sequences tell the games story in a different narrative and sometimes are simply there for entertainment purposes.
Gears of War uses scripted sequences between sections of game play to provide objective reminders and tell the games story without the use of cut scenes. The game triggers a playable scripted sequence once all of the enemies have been cleared in an area, usually these sequences play while the player moves to the next area.
Resident Evil 4 has many examples of scripted sequences that utilize a quick time event to feature more action packed game play. As the player navigates the level, they must react to the event to continue.
Games such as Call of Duty have been criticized for a reliance on these sequences, as many feel they tend to guide a player through a game by the invisible hand of the developers, blocking progression with invisible walls until the scripted sequence has triggered further progression. Also, the use of scripted sequences may diminish replay value as the surprise effect is negated upon subsequent play-throughs.