I've just uploaded the Onslaught v4.1.8 release file. It should be available for download shortly.
Don't be fooled by the version number; this is a major release, and is intended to be the final version. Several ships have been re-textured, a number of bugs have been fixed, the hints section has been improved, new maps have been added and the game play has been overhauled in response to the comments of experienced Cataclysm fans. Visually the most noticeable changes are to the Beast Carrier and Beast Battlefield Frigate, both of which have been faithfully re-textured as repaired versions of the original Homeworld Derelicts, and the replacement and reworking of mothership support modules on both sides. Onslaught is now as faithful and complete as I can make it. I've left the possibility of a v4.1.9 open should any bugs appear, but otherwise this is the final release.