KiTTY is a fork of PuTTY (started from version 0.62 beta), the most popular Telnet and SSH client for Windows and Unix. It runs on Windows and it has an impressive collection of one of the most requested features that are missing from PuTTY. Here is a list with most important features: sessions filter, portability, predefined command shortcuts, session launcher, automatic log-on script, URL hyperlinks, automatic command and password, running locally saved scripts in remote sessions, ZModem integration, icons for each session, transparency, unfortunate keyboard input protection, roll-up, quick start of duplicate sessions, configuration box, automatic saving, Internet Explorer integration for SSH Handler, binary compression, clipboard printing, PuTTYCyg patch, background images/transparency, organizing sessions you save in a folder hierarchy and many others that are constantly added. You can find a complete list of its features on the main page - including a description for each one.
Important: Please note that the use of KiTTY could be illegal in countries where encryption is outlawed. Although, I have no authority to provide more information, this website "The Crypto Law Survey" could be a good place to start. However, I am not associated and I do not offer any guarantees that the information found there is accurate. Therefore, if you're in a country where encryption has any legal limitations or it's forbidden you should seek legal advice.
Note: There's no installation process, just download KiTTY and run the program instantly.
Perhaps, the word "a fork" is a little bit unfair for KiTTY project. After all, although all Linux platform looks and act almost the same, there are several notable differences between them. In this case, the only advantage of PuTTY would be: the ability to run on Unix (Linux) platforms while KiTTY is limited only to Windows users. However, KiTTY has its own advantage: it can perform all the tasks of PuTTY plus it's own collection of features that are missing from PuTTY (keep in mind that the latest version of PuTTY was released in 2007).
After playing with this application I came to this conclusion: you can count on the same stability and reliability that the old PuTTY has to offer. The design it's the same, the learning curve it's close to zero if you used PuTTY before and it brings loads of new features. As a conclusion, if you miss a new version of PuTTY, switch to KiTTY - it might be the perfect substitute. If it is, the author would also appreciate a small donation.