As a product marketer, I have to say that the name is very unfortunate.
1. Sundown is the name of a Markdown library written in C: https://github.com/vmg/sundown. That Sundown is pretty widely known and used among Markdown implementers. As such, when/if the OP's project takes off, it is going to be confusing (for awhile).
2. Also, the name itself doesn't strongly suggest that it's an alternative to Markdown. Do recall that Markdown's etymology comes from "(HTML) markup". For the Markdown-implemented-in-C Sundown, the name worked because it evoked its relationship with Markdown. In this case, that's not what the project is about. If the intention was to evoke Markdown, then they should have kept the "Mark" part of it, not the "down" part of it.
1. Sundown is the name of a Markdown library written in C: https://github.com/vmg/sundown. That Sundown is pretty widely known and used among Markdown implementers. As such, when/if the OP's project takes off, it is going to be confusing (for awhile).
2. Also, the name itself doesn't strongly suggest that it's an alternative to Markdown. Do recall that Markdown's etymology comes from "(HTML) markup". For the Markdown-implemented-in-C Sundown, the name worked because it evoked its relationship with Markdown. In this case, that's not what the project is about. If the intention was to evoke Markdown, then they should have kept the "Mark" part of it, not the "down" part of it.