Greek Finance Minister Yannis Stournaras said the privatisation had been "successfully completed". However, he gave no further details and did not disclose the final sum paid.
The fund had been urged to bid at least 650 million euros, though the stock market values Opap at just 726 million euros.
Greece is obliged to raise 9.5 billion euros from asset sales by 2016 under an international bailout plan. In return, the European Union and the International Monetary Fund have committed to 240 billion euros since 2010 in rescue loans for recession-hit Greece.
Uncertain revenues
OPAP has a 10-year licence to operate 35,000 video lottery terminals, as well as the exclusive rights to operate 13 games of chance until 2030. However, Emma Delta has said that there is much "uncertainty over future revenue streams" and that it has identified "internal structural problems" at Opap. Last year, OPAP made net profits of 505 million euros, a 6% fall when compared with 2011.
A rival bid for OPAP, placed last week by US investment fund Third Point, was not accepted as it violated the tender rules by including conditions. Six others that had expressed an interest in OPAP did not place bids.