The hack, which is for the Japanese-exclusive Super Famicom version of Clock Tower from 1995, restores various cut content and unimplemented features from the later PlayStation version, along with applying several bug fixes and quality-of-life changes. This includes welcome additions like mouse support, the ability to run through stairs, faster health regeneration, and an optional way to speed up credits.
Now it seems that its creator has come back to this project to release a new update — the first in over two years — as spotted by @CDRomance_Spike on Twitter.
This new update incorporates an optional new chase system into the game, which allows the Scissorman to follow you door to door instead of "teleporting" around, and has them appear randomly while you're exploring the different rooms of the mansion. More unused and cut content has also been included in this new patch, such as new hiding spaces and single-use defense items, and there's now even a save file protection failsafe that will stop you from accidentally choosing "NEW GAME" and deleting your progress.
To install the hack, you'll need to apply one of the compatible translation patches (the list is available here) to a Japanese ROM of the game, before installing this latest update. It's supported on the SNES as well as the original Super Famicom with a Super NES mouse.
More instructions can be found on the RHDN page, but one thing that's important to note is that ROMs with previous versions of the hack installed should not be updated, as it can potentially lead to crashes.