D.C.
This adventuresome 2-yr-old sounds like he has an awesome mom!
I have three boys who have all gone through late speech development. One of the things I tried was, like the person said in the previous response, to repeat the word back at him with the word correctly pronounced. Also, I would try something like "I don't understand what you want. Are you trying to say you want to play?" and ask him to attempt to say his sentence again. Whether or not he says the word correctly the second time, give him some positive reply, like "I bet what you want is to go play".
With this approach I tried to not automatically accept his mispronounciation. My youngest started leaving off the last consonant of a bunch of words (milk was pronounced mil, for instance) and I realized that I was responding as if that was acceptable. My son didn't mind repeating what he was trying to say and, gradually, improved quite nicely.
Good luck!