It does, just very slowly - later levels have words that fire other words at you. It's surprisingly fun. There's a lot of potential here for game mechanics like achievements, challenges, leveling up.

I think the game is a bit too easy for good typists. Spaceships will start shooting words at you pretty early on (level five was when I encountered one) but only if you are slow enough to let them. (I’m not a very good typist and didn’t even make it beyond the fifteenth level.)

It starts to get more difficult around level 40 or so. I made it to 51: http://i.imgur.com/McY0g.png

When there's a lot of large words coming down at the top of the screen, the app definitely began missing input. I'd type a word correctly, but it would not recognize a character, so I'd have to context switch from deciding on which word to type next to finding which one was partially finished. Fun game, anyways.

Running Chrome 8.0 on OSX 10.6.5

Right around level 27 or so these baddies come in that shoot probably 20 or so individual letters at once at you, and that's when things start getting a bit more interesting...