Space Quest II is the tenth Sierra title to utilize the Adventure Game Interpreter (AGI) engine used in other Sierra games like King's Quest and Leisure Suit Larry. The engine interface uses a text-parser-dictionary system to recognize words that are typed in. For example, look describes the room you are in. Look clothes describes what you are wearing.
The game's dictionary often groups words with similar meaning together. For example, "look" and "examine" mean the same thing. Similarly, "clothes" and "suit" mean the same thing.
The common format for entering a command is <verb> (<noun(s)>). Adjectives are considered part of the noun they are describing. Prepositions and articles (for example, "in", "on", "to", "the", "a") are optional since the system ignores such words. Occasionally, the game accepts just <noun(s)> if in reference to something iconic, such as a labeled button. Verbs and nouns may be more than one word.
According to the manual, here is a list of verbs that the game recognizes:
Keep in mind that these are not the only verbs that the game recognizes. Note that "look" substitutes for "examine". There are also verbs, such as "wait" and "sleep", even if they don't do anything constructive.
If the game does not recognize your input, it will say "I don't understand your request" or "That does not compute" or "Say What?". If a particular word is not in the dictionary, it will say "I don't understand '<word>'".
The gameplay is classic trial-and-error adventure. In other words, saving is part of the gameplay. Save early, save often, and don't overwrite saves. Use as many saves as you need; there is never such thing as too many saves.
Be forewarned that it is possible to end up in situations which are impossible to win, which may not be known until later.
It is expected that the gamer experiments thoroughly and has reasonable problem-solving skills.