Hi !
if you like video editing and adding a lot of effect , you certainly miss AfterEffects , even if blender is realy good , the interface is not very user friendly.
There is an alternative called Natron : http://natron.fr/
i think it should be added to the software boutique with shotcut https://www.shotcut.org/ an excellent video editor
Neither are available via a repository or PPA so can’t be added to the Software Boutique 
Could recommend for the game category Retroarch, which is an open source, multi-platform frontend for libretro cores(game emulators).
Think this is the PPA: https://launchpad.net/~libretro/+archive/ubuntu/stable
Any chance Audacious and SMPlayer will be added to the Software Boutique in the future?
Audacious is a great lightweight music player which supports Winamp skins as well as video game music files and SMPlayer is a nice graphical front-end for MPlayer and mpv.
I have suggestion of adding peerguardian
They have ppa
sudo add-apt-repository ppa:jre-phoenix/ppa
sudo apt-get update
sudo apt-get install pgld pglcmd pglgui
I find it useful.
For more info please check it on https://sourceforge.net/p/peerguardian/wiki/pgl-Install-DebianUbuntu/
I would like if you can consider and add it to software boutique.
Hmmm…
I guess that peerguardian may not be compatible with Ubuntu Mate 16.04.
Worked great with all previous versions. pgld depends on netfilter support in the kernel . We may need to wait for update.
So they can be in the Boutique… 
Natron Repository : https://github.com/NatronGitHub/Natron
Shotcut Repos : https://github.com/mltframework/shotcut/
and shotcut is even as a snap : snap install shotcut --classic
Nintendo and Service Games / SEGA international would like a word with you. 
They must be thinking of my twin, Warm.
Anyway, emulators are legal(for now…).