A_ExtChase

From ZDoom Wiki

A_ExtChase (bool domelee, bool domissile [, bool playactive] [, bool nightmarefast])

Warning: The feature described on this page has been deprecated, and will no longer be supported or updated by the ZDoom developers. While some functionality may be retained for the purposes of backwards-compatibility, authors are strongly discouraged from utilizing this feature in future maps. Compatibility with future ZDoom versions is not guaranteed.

Note: This function has been superseded by A_Chase, which duplicates and extends its functionality. Use of the newer function is advised in order to maintain maximum flexibility in your code.

This is similar to A_Chase but you can specify whether a monster is allowed to enter the melee or missile attack state.

You can also optionally disable playing of the active sound which is done by A_Chase normally.

if nightmarefast is non-zero the monster will also move faster on Nightmare skill or corresponding skill levels on the other games.