The gameplay takes place over a four-day period and the player is required to complete specific tasks and puzzles before proceeding to the next day. Zero Critical uses the point-and-click approach to move around, find and use inventory objects, examine items and communicate with other characters. Conversations take place through a dialog box with pre-programmed questions and responses to progress in the game when talking to other characters. There is no voice acting in the game, however there are lots of conversations but they are all done in plain text. Conversations are initiated by clicking on a character or showing them an object. It is possible to choose various paths for the conversations. Asking questions normally generates new ones that are added to your list of possible queries. The player's PDA automatically stores dialog transcripts, this allows the player to go back and check on a comment he may have missed.
