For the Fungus Asset Package, which you can get here: https://github.com/snozbot/fungus/releases
This allows you to set up timers for things like countdowns and tracking how long things took. Yes, even how long the player has been playing your game ^^
This was made with Fungus 3.13.0 (compatibility version) in Unity 2017.4, with the master branch project set for Unity 2017.4. It should work well for those versions and later.
Go to https://github.com/CG-Tespy/TimerSystem/releases/ and download the unitypackage for the version you want. When the package is done downloading, open your Unity project and install the save system through that package.
Please be sure to check the wiki for them. https://github.com/CG-Tespy/TimerSystem/wiki
If you are using this in one of your projects (or you have any questions), I would very much appreciate it if you'd let me know. Just send me an email at gbcabreracgt@gmail.com