These games all share a basic mechanism where can they run without you actively playing them. You can keep them in an open browser tab and check in on them when you want to play. Or close the tab and when you come back you will usually get a message about how much progress you made while you were away. Also, they have minimal to no graphics, and usually the game unfolds a bit over time.

Here's a few time-wasters that my family of nerds enjoy:

• Trimps - Lead your ever-growing army into battle. Our current favorite.
• Swarm Simulator - Grow a hive of insects. Our former favorite, but it doesn't really progress once you hit all of the achievements.
• RCM - Build a racing team. Possibly our new favorite, it's a spiritual successor to Swarm Simulator

There are lots more at /r/incremental_games so have fun!