I'm thinking of games like Animal Crossing, which encourage you to play of short periods of time (like 20 minutes) but regularly, for example everyday, and where playing for hours straight make no sense. Is this type of game have a specific name ?
The term that comes to mind, as @djsmiley2k mentions in the comments, is casual. While not a perfect source, Wikipedia describes a casual video game as (emphasis mine):
- Extremely simple gameplay, like a puzzle game that can be played entirely using a one-button mouse or cellphone keypad
- Familiar genre, like a card game or board game
- Allowing gameplay in short bursts, during work breaks or, in the case of portable and cell phone games, on public transportation
- The ability to quickly reach a final stage, or continuous play with no need to save the game
- Some variant on a "try before you buy" business model or an advertising-based model
Whilst it's possible to play a game like Animal Crossing , Plants vs Zombies or Angry Birds for hours on end, it's also possible to play for a short period of time.
The Steam store also has a tag for casual games which lists Plants vs Zombies and Angry Birds amongst others, though doesn't go on to define what a casual game is; however, Steam tags are user-defined