As you may know, Up Clock is a widget style clock inspired by the Ubuntu Touch lockscreen. Among others, it allows the users to choose from 10 different colors and choose a color that integrates with the background, change the displayed time type (12 h or 24 h), adjust transparency. Also, it notifies the users at a specified time exactly, like an alarm clock.
The latest version available is Up Clock 5.5, which has been released a while ago, but recently, its PPA got packages for Ubuntu 15.10, Ubuntu 15.04 and Ubuntu 14.10.
Up Clock is available via some third party PPA, so installing in on Ubuntu 15.04 Vivid Vervet, Ubuntu 14.10 Utopic Unicorn, Ubuntu 14.04 Trusty Tahr, Ubuntu 12.04 Precise Pangolin and derivative systems like Linux Mint 17.2 Rafaela, Linux Mint 17.1 Rebecca, Linux Mint 17 Qiana, Linux Mint 13 Maya, Pinguy OS 14.04, Elementary OS 0.3 Freya, Elementary OS 0.2 Luna, Deepin 2014, Peppermint 6, Peppermint 5, LXLE 14.04 and Linux Lite 2 should not cause too many problems.
Just add the PPA to your system, update the local repository index and install the up-clock package:
$ sudo add-apt-repository ppa:apandada1/up-clock
$ sudo apt-get update
$ sudo apt-get install up-clock
Optional, to remove Up Clock, do:
$ sudo apt-get remove up-clock