This game is often described as being written in another language, but it's not another language per se, just English with a totally foreign vocabulary. However, it does do a pretty good job of simulating the experience of trying read a foreign language where you have a good grasp on the grammar but a regretfully small vocabulary :) How far you make it depends on how well you can navigate the linguistic maze and assign tentative meanings on the fly to words you've never encountered before. (For the record, I never made it very far.)
A tip for you: type "jallon" at the start to view the help. It... could probably be more helpful, but that's half the fun, right? You should be able to figure out enough verbs to get you started.
Finally, here you are. At the delcot of tondam, where doshes deave. But the doshery lutt is crenned with glauds. Glauds! How rorm it would be to pell back to the bewl and distunk them, distunk the whole delcot, let the drokes discren them. But you are the gostak. The gostak distims the doshes. And no glaud will vorl them from you. The Gostak An Interofgan Halpock Copyright 2001 by Carl Muckenhoupt (For a jallon, louk JALLON.) Release 2 / Serial number 020305 / Inform v6.21 Library 6/10 Delcot This is the delcot of tondam, where gitches frike and duscats glake. Across from a tophthed curple, a gomway deaves to kiloff and kirf, gombing a samilen to its hoff. Crenned in the loff lutt are five glauds. >help That's not a dape I recognise. >x me That's not a dape I recognise. >t me You're as tunky as ever. You are rasking: your shamtag (which is lelloed) A naft of gitches pells at the hoggam. >t shamtag It's a snave and sharmy shamtag that flomes when you durch it. Its dugrid is lelloed. The shamtag is currently riked gemmly. >unrike shamtag That's not a dape I recognise. >rike What do you want to rike? >shamtag (riking the shamtag gemmly) That's already gemmly. >t gitches They deave in the hoggam and frike out to zank warbs. A warb degombs the brangy. >t warb A lurpid warb of the brangy. A gitch frikes from the hoggam to zank and leil the warb. >rask gitch You rask one. >i That's not a dape I recognise. >rask brangy That isn't available. >t warb You can't reb any such thing. >t (the Delcot) Delcot This is the delcot of tondam, where gitches frike and duscats glake. Across from a tophthed curple, a gomway deaves to kiloff and kirf, gombing a samilen to its hoff. Crenned in the loff lutt are five glauds. A gitch tunks you from the hoggam. >t duscats You reb no duscats here. (A delcot without duscats? Hmm.) A warb degombs the brangy. >t glaud Which do you mean, the raskable glaud, the poltive glaud, the glaud-with-roggler, the glaud of jenth or the Cobbic glaud? >raskable A raskable glaud is about as unheamy as a darf of jenth, but at least it can vorl the doshery from the gitches. A gitch frikes from the hoggam to zank and leil the warb. >kiloff Gomway You're on a gomway deaving hoff, with gropples on the fosk. There's a stike across the gomway here, and the delcot is to jirf. >t stike The stike deaves across the gomway.
If you like the idea of a text adventure that plays with language, but would rather try something less horrible, there's For a Change.