If one of the representatives of the hardware community has calculators from Texas Instruments (models TI-83 and TI-84), you can diversify your leisure time by playing Portal. True, not to the colorful version that we saw on other, more powerful platforms, but the game is quite a decent one. Demonstration toys - in the sequel.
Developed this game is a third-party programmer, Builderboy2005. Along with the game comes even a level editor, i.e. quite a decent game. Currently 38 rooms / levels available.