Hardcore music in Croatia currently sucks. But I can tell you that Croatia used to be a part of the country of Yugoslavia which had the best hardcore punk scene in the 1980s and 1990s! Yugoslavia consisted of 6 countries and of those were Croatia, Serbia and Slovenia - the countries that some of the greatest hardcore punk bands evolved from.
80s Yugoslavian punk was the best because there were a lot of awesome bands. Punk just came here to Yugoslavia and everyone wanted to be a part of it so ppl started forming bands, really good bands which everyone knew about. Serbia, Croatia, Slovenia - we were all so friendly and had a lot of gigs throughout whole Yugoslavia. This scene was sooo hyped and everything. We don't have this nowadays. So we can say that current scene is kinda on hiatus.
I'll write some bands for you. These are a few of the ex-yugoslavian hardcore punk bands:
U.B.R. (Uporniki Bez Razloga)
Make sure to check this blog out, has a lot of Yugoslavian hc punk mp3s.
Punk rock in Yugoslavia