After a long time away, Monster Hunt for UT99 has begun receiving official updates again.
The latest version, 605, is available in the Files page.
In addition to many server and stability improvements and optimisations, the new versions also introduce a new game type called Monster Defence. This is played on regular CTF maps, where you and your team must defend one of the bases while an endless assault of monsters tries to attack and escape via a portal that replaces the flag.
More updates with features and fixes will be added in the future as well.