TUG are being addressed by the team and its security measures, Nerd Kingdom wrote in a forum post yesterday.
Players noticed something wrong when they couldn't log into the game yesterday, and a developer confirmed that a DDOS attack was in the works and was being combated. She said that there is no ETA for a fix but that players who have applied for testing keys need not worry about losing theirs due to the issue.
"Yeah, the attacks started during the weekend and they've been pretty relentless. Luckily our security measures are working. We just need to do some tweaking now," developer Dee posted. "While it sucks that it's happening, it's better to have these things happen now, while we're in the alpha stage when stuff's supposed to break, than later when it might've been much more of a problem to iron out."
[Thanks to Sounder for the tip!]