Thanks for the replies! I have successfully installed Divergence IV theme and AwOken icon set and I'm pretty excited :)
Can you please tell how to install Emerald on Mint Mate 18, because there it is nowhere to be found in the official repos and many of the non-official are for older versions, can I get it from some official site or probably the source in order to compile it myself? I really want the transparency effect + AWN dock :)
I haven't heard of an Emerald theme before, are you talking about this one
? (probably not though, as it says it only worked with unity and gnome-fallback, so it might not work on mate...)
edit - I just found out (after I posted the below explanation on installing old themes) that Emerald is some sort of window decorator for Compiz - I personally use the default Marco/Metacity so I don't know much about Compiz, but there's a possibility the emerald themes might be old too, so hopefully all the stuff I wrote below will still apply...)
At any rate, whichever theme you mean, for themes that might have been included in a PPA for an older ubuntu base, a way to check and see if they could be compatible with the current version would be to unzip the deb file.
I'll explain what I mean; suppose you want to install the theme I mentioned in the above link. In order to get the deb file, you copy from the install instructions the ppa:noobslab/themes part and search for it e.g. on google. You then find as the 1st search result the link to the PPA. In that page you see all available packages and can filter by ubuntu release. Click "view package details" (in small letters in the right side) and search for emerald -from the results it's obvious the last release of this one was for trusty (14.04) -clicking on the pack shows you the download link, click it and get the deb file. Now right-click (do not left-click) the deb file, click "open with" and open it with an unzipper - I personally use PeaZip rather than the default program for such an instance, but it might work with the default program too. You'll see a data.tar -open that too, and click through the directories in that file - you'll probably see something like ./usr/share and under that are the files you want (the example I gave is badly picked as it has a more complex file structure than anticipated -in this case I'll take the xenlism wildfire icons deb file - unzipping it shows data.tar/./usr/share/icons and then the icon themes). Unzip the file as usual and put the unzipped folder in /home/leon30/.themes or .icons. Then go to the appearance menu and go to the "controls" or "icons" panel and find the pack you just unzipped in .themes or .icons -apply it and see how it goes.
If this all sounded complicated its because it kind of is - I mainly use this tactic for getting deb files when I don't want to add the PPA of something for whatever reason and use the tactic of unzipping the deb file in regards to themes and icons in order to avoid accidentally adding dependencies that could ruin my pc -I once installed the Kylin icon theme 2 months ago and didn't notice it installed some other stuff, including its own version of D-Bus which ruined my keyboard languages switcher (that was awful as Greek -like Bulgarian- is a non-latin language, so I couldn't make do with the english keyboard), I had Ubuntu Mate installed at the time though, so I just wiped it and installed Mint Mate instead.
In short, it is kind of complicated to try and apply an older icon theme that's only available as a deb file and not as a regular zip or tar.gz, and you should generally try to avoid such themes if you can find current replacements or replacements with a simple zip/tar file instead...
Hope this lengthy explanation will be of some help to you...