gambling has proved to be the downfall of society, refrain from it.
that being said, since people from other countries are playing (assuming), then you are fine since their laws do not affect you (etc. greece). How ever, the USA government could ask you to shut it down if you do not have the license to run a gambling facility/website.
Is starting an online chess gambling site like online poker sites illegal? I've heard that because chess is a game of pure skill it does not fall under the typical illegal status in the United States. Is this true? Supposing that online chess gambling was legal in the United States what would happen if players from outside the United States started using the site? Could the company running the site from United States be in legal trouble with regards to the law in other countries because their citizens accessed the site and gambled?