Fans hoping to see the season four opener of the fantasy drama, starring Peter Dinklage and Emilia Clarke, were disappointed when they could not watch it online after the sheer volume of viewers brought down the channel's Go service.
A statement from website bosses, posted on Twitter.com, reads "Looks like there's trouble in the realm. Apologies for the inconvenience. We'll be providing updates, so please stay tuned."
The news comes less than a month after the finale of Matthew MCConaughey's crime drama, True Detective, caused a similar crash.
A statement from Hbo, obtained by The Hollywood Reporter, reads, "Hbo Go did experience issues due to overwhelming demand around the premiere of Game of Thrones. The service has returned to several platforms and we are working hard towards full recovery, which we expect soon."