Try to beat this game!

I'm sure there's a simple rule behind it, but it's too late at night for me to figure it out...

<a href="http://www.ebaumsworld.com/pearl.shtml" target="_blank">Game</a>

This reminds me of one of my greatest accomplishments in life... :sigh:

In high school, my friend programmed a computer game called "21". It was similar to that game. The object was to type either a 1, 2 or 3. Then the computer would do the same, and add up each number that was previously typed. The first player to reach 21 or higher lost.

I beat the game a couple of times, and then my friend said, "I'll put it on impossible now...". I typed a 2, the computer typed 1... I paused. Then I typed "2.4". A bunch of nonsense letters took over the screen and then "You Win" was displayed at the bottom.

That was the defining day I knew I wanted to program games at some point in my life... like it was some sort of calling. It makes me feel good whenever I think about that moment.

Damn that game is hard.

After playing for about an hour, I found <a href="http://world.std.com/~reinhold/math/nim.html" target="_blank">this</a> (spoiler).

Yeah, it took the fun out of it, but that guy's laugh was going to stick in my head and annoy me until I beat it.