As if you needed more distractions from class, Reddit user Builderboy2005 has created his own version of Valve's hit game Portal for use on TI-83 and TI-84 calculators. Unlike the original game, which uses a first person perspective, Portal Prelude is a side-scrolling platformer filled with 38 test chambers to make your way through with the help of your trusty portal gun. The game's creator says it took several years to create, and the scripted dialogue that is interspersed throughout shows his close attention to detail. Take a look at the video below to see Portal Prelude in action, and if you have one of Texas Instruments' graphing calculators handy, feel free to download the game for yourself.