I think that OP is located in a crypto gambling ban area. For instance, currently in italy there is a DNS block/redirect to the site of the italian gambling authority.
I think that is probably the problem. I accessed the website easily on a smartphone from Hungary. No blocks, no bans, no warnings:
However, since the op assumed the website closed, it mist likely means that this person was able to use it before. I could be that the op moved to another country, or maybe Bitstarz stopped offering services for some new countries recently. Another guess is that the op'd IP might have been blocked from entering the website for whatever reason. So there are actually many possible answers, and it would be easier to determine the right one if the op provided more info on the case.