The Shakespeare answer reminded me of Inform 7, which is a serious programming language for writing interactive fiction. It's probably the language most closest to English that exists and has a well-defined semantics.

Here is a sample from Wikipedia:

"Hello Deductible" by "I.F. Author" The story headline is "An Interactive Example". The Living Room is a room. "A comfortably furnished living room." The Kitchen is north of the Living Room. The Front Door is south of the Living Room. The Front Door is a door. The Front Door is closed and locked. The insurance salesman is a man in the Living Room. "An insurance salesman in a tacky polyester suit. He seems eager to speak to you." Understand "man" as the insurance salesman. A briefcase is carried by the insurance salesman. The description is "A slightly worn, black briefcase." Understand "case" as the briefcase. The insurance paperwork is in the briefcase. The description is "Page after page of small legalese." Understand "papers" or "documents" or "forms" as the paperwork. Instead of listening to the insurance salesman for the first time: say "The salesman bores you with a discussion of life insurance policies. From his briefcase he pulls some paperwork which he hands to you."; move the insurance paperwork to the player.

The sample uses an extensive library of objects which is available for user. But the language itself is in fact Turing complete, and you can define objects with any behaviour in it.