https://www.awesomenauts.com/ no longer carries linux downloads for this game. Mac/Windows users are redirected to Steam. According to http://indiegamebundle.wikia.com/wiki/The_Humble_Indie_Bundle_8, "All games in this bundle can be downloaded DRM-free for Linux, but download links for Awesomenauts have been silently deleted on August 5th, 2014. Steam keys still available." Given that only users that downloaded this over a couple years ago will be able to make use of an ebuild, perhaps this ebuild should be last-rited.
Very odd that Humble Bundle removed the download, it's not like they were relying on the developers to host it and it's unlikely that it would have just stopped working. I do have this game but never downloaded it myself. Last-riting it might upset those who have it installed already but it wouldn't be the first game that's now Steam-only. I'll go ahead and see if anyone shouts.
It's gone.