If we wanted to define a brand new verb that did affect a specific object, we might begin like this:
Of course, how our players will ever solve this problem is another question (especially if their biology and chemistry are both rusty). When adding entirely new commands to a game, it is often a good idea to provide as many ways of phrasing the command as possible; to drop hints about the correct phrasing within the game's text; or even to tell the player about the expanded command list in some documentation or help at the beginning of the game. So for instance we might also add
And these lines will also provide syntax for our new command, without interfering with the previous syntax. It's also good to anticipate alternative (British or American) spellings. People's typing habits are hard to overcome, even if they know you are spelling the word the other way. It is probably best not to annoy them unduly. So:
Then some text in-game might offer a clue, subtle or (since this is an example) blunt:
And finally, we could try adding instructions explicitly:
Test me with "x xylan / hydrolyze xylan / x xylose".
You can see a xylan sample here.
> x xylan
A polysaccharide. Totally useless. If only you had some xylose, instead!
> hydrolyze xylan
At once the xylan becomes xylose.
> x xylose
…though of course in fact these other commands won't be available until we define them, too.
This last approach, defining all the extra commands up front, is especially useful if these commands are very technical or unusual; if they are needed early in the game, before you've a chance to educate the player; or if they are not suggested by any in-game objects. A player who encounters a tool with an obvious use, such as a hairbrush, will likely think of trying to BRUSH things with it. It's harder to rely on his guessing actions that are both outside the range of usual commands and unrelated to any of the visible props, however.