Text adventures arrive on the DS via unofficial channels
We can't tell you to download them (in fact, we'll tell you not to), but we can definitely applaud the technical achievement. A homebrew genius called papafuji has ported a massive selection of classic text adventures and early graphic adventure games to the DS, including all of Infocom's text adventures and Hitchhiker's Guide to the Galaxy author Douglas Adams' interactive fiction.
These aren't just barebones ports, either: you can save games, and you can choose to enter text via an onscreen keyboard or handwriting input! And the game engine contains shorthand functionality for common commands like cardinal directions and "get".
Some of the games are public domain, but most aren't, and we aren't sure which games fall in which category. Therefore, we're officially warning you: if you download these games, there's a good chance that you are a pirate.