Metroid Pi is a pure TI-Basic version of the classic Metroid game, with the game following the standard storyline of making your way through several increasingly difficult areas, while battling enemies, bosses, and getting powerups that allow you to beat the next area in the game. The game utilizes the graph screen throughout, making use of the layered graphics technique that Super Speler came up with in his Zoith game, but the sprites themselves are still reminiscent of the home screen text.
Of course, none of this is cheap in the memory department. The game takes up over 17KB, with it spread out over seventeen different programs (in particular, each of the three bosses and three maps are given their own program), and you need to have each of these files unarchived in order to actually play the game. Of course, this does not include the actual in game usage that occurs from using all of the lists, strings, and real variables, which is another 5KB of memory.
Still, the game is a great achievement in TI-Basic, and surely stretches what people thought is possible.