I can't find New Delhi, India's timezone. It's missing!

No, no it's not. VistaClock uses the IANA Time Zone Database. This database contains every timezone in the world. It's just a matter of finding it. The easiest way is to look for the GMT offset of the timezone you want. And then you search for that number in the list and find a city in your timezone that corresponds to it. For example, India has *one* timezone, GMT+5.5. Looking in the list delivers "Asia/Kolkata +5.5" which is indeed the correct timezone for all of India.