Without having the source code, it is obviously a bit hard to judge, but let's have a shot at it. There are various possibilities to "guess what the player meant":
- Levenshtein distance, as you said - Possible, but probably a bit heavy for an 8-bit micro and (only) a command line interpreter - Also maybe a bit oversize for a fixed set of strings to match against
- Soundex algorithm - That is way simpler because it is purely table-driven and the soundex table is typically very small - Look it up, I guess that is how it's done (especially because it ignores vocals completely as in your examples). You can check it here against the keywords understood by the game (Note some soundex algorithms ignore the first letter of the word, some - as the one on the website- don't)