The Productivity Enforcement Daemon enforces productivity by killing timewasters while productivity is insufficient.
Measuring productivity is difficult, but the easy way to measure productivity is to check with an external todo list.
Since I use Wunderlist, that's what prodenfd supports.
Detecting wasted time is difficult, but the easy way is to kill a process if it's running.
Since I play a lot of Steam games, that's what prodenfd supports.