There's a text-based interaction/dialogue system which can be used for some objects and NPCs. You can Look, Investigate/Touch, Speak and Take. The certain GUI icons will shine if some of these actions are available. In this video I'm showing a simple example using a help of test object Cubie.
Look (press "1" button) - Protagonist will make a comment about the object.
Investigate (press "2" button) - He will investigate it and you'll get more information
Speak (press "3" button) - He will speak with some NPC (press Enter and Arrows to proceed)
Collect (press "4" button) - He will take some item
Original 16:9 version is available on YouTube: Youtube.com