Heroes of Newerth players were unable to get their DOTA-style gaming fix from the online game following what's being called a "catastrophic hardware failure" that occurred during an update this week. The failure happened during downtime for hardware upgrades yesterday and resulted in the destruction of both the game's server and database boxes. A post to the official forums explains the event in more detail:

We attempted to upgrade the processor on our database boxes. Both of our servers were simultaneously taken offline while the new hardware was being put in place. During this period of time, the file systems on BOTH boxes were destroyed. If this boggles your mind to the point that you can't believe it could happen, you would be in the same exact boat we are! It seems almost statistically impossible, however, it is in fact what happened.

This leaves us with no hardware to operate our DBs from until we can get new servers online. The reason for such a catastrophic situation is that this hardware is not the type that is simply sitting around, even in the largest hosting facilities in the world (in which we host at). We are scrambling to bring our systems back online temporarily so you can play the game through other short term methods while we get new hardware online.

Luckily, the team had the capacity to recover from the damage and has been able to restore services through temporary means while they replace the destroyed hardware. In the meantime, the devs have offered an apology and compensation to players.

Sources:

Heroes of Newerth Forums

Kotaku