Python AI (Artificial Intelligence)

Just for fun,  I decided to make a little person in the computer. One that would respond to questions. I have done this before with Ruby, the first programming language I learned, but then I had a big problem. The program would check if the player typed "want to play a game?", and it would so stuff. But what if someone said "Hey, wanna play a game?" The computer would read it as something totally different. But today, I got an idea. What if I had it so it would respond to certain words in the string of whatever the user typed in? For example, it would look for the words "play" and "outside", and if the user typed something that had those two words, then it would do things. If the player said "hey, do you want to play outside?", and "can you play outside?", it would read them as the same thing. They both contain the words "play" and "outside". I'm going to try and program it to respond to certain questions, and I may use Siri, Apple's AI guide, for inspiration. Copy some of the same questions that you can ask Siri. The only problem is, it will be very time consuming. "Grunt work", if you will.