Snowman 1.0.1, 43 bytes, cracked by Kslkgh

[[IO::print]]((("Hello, World!"[[end;]]sP))

Explanation:

The basic "Hello, World!" program is actually just ("Hello, World!"sP. Anything surrounded in double parens, i.e. (()), is in its own environment. In this case the new environment doesn't affect anything. Anything in double brackets, i.e. [[]], is a comment, so [[IO::print]] and [[end;]] are just for show.