Gravity shift based physics puzzle platformer. 7 hours or so.

4 hours if you follow a guide. Matching up everything will still be quite difficult as the order is randomized and many pieces sound almost identical.

Frantic run,shoot and dodging game. About 11 hours. Your time will vary significantly depending on how well you play, as you'll need to complete most levels (about 2 minutes long each) near perfectly.

First person exploration. 1 hour.

2D walk and shoot. 1 hour.

First person exploration. Half an hour if you follow a guide.