Survival sequence

Implied:
* Timed sequence

Related:
* Escape sequence

Usually there's a notice that a transporter is inbound in ~3 minutes and the player must survive until it arrives. Player is usually confined in a small area with limited resources and so forth. Player has no way to progress other than simply staying alive, killing opponents has no effect besides slightly improving chances of survival but the enemies likely (abnormally) respawn endlessly.

Note that if this is finished by killing, destroying or disabling the opposition, then consider it a case of elimination sequence.