It's a non-profit site created by a former Reddit admin Deimorz (known for being the creator of /u/Automoderator, /r/SubredditSimulator...).
It's currently in closed alpha so the community is somewhat exclusive because of that; but if you wanted a HN+reddit hybrid, then it might be worth checking out.
I already have a Tildes account. It's not really active so I haven't checked it out very often. They are very careful about community growth so I don't see how it will become a competitor to Reddit, as least not in terms of business value.