Seriously - if you can attach a .capx then .c2addon should work as well - the way it is now it's annoying to either the maker, the users or both - you either rename the zip or put the renamed zip in a zip or put it up somewhere else where no download counts are present and the users can't be sure it will be available after a while.
Develop games in your browser. Powerful, performant & highly capable.
Yeah, seriously, just do this. Tom
For now attachments are taken down, but once the bug is fixed, this should be implemented in.
Keep your finger crossed Tom can fix the attachment bug, it's a mean one currently.