You have to go back a few years to when graphing calculators such as the Texas Instruments TI-83 Plus and TI-84 Plus series models were hip and trendy, they even had the odd game on board too. However, gaming has moved on, which is probably why we are looking at Portal Prelude game play for these cool graphing calculators, check it out in the video below.
Here are the details for the Portal Game for graphing calculators;
This is a video of Portal Prelude, a Portal fan game by Builderboy2005 for the TI-83 Plus and TI-84 Plus series of graphing calculators, similar to the Flash clone for being in 2D. It was finished and released on December 1st 2012 at http://www.omnimaga.org/index.php?action=downloads;sa=view;down=841
Source [Geeko System]