Especially when the capital ships start shooting!
You can complete a level -- but then a new, faster one starts. Change the semantics to "You won Level N!" and add an optional cookie to remember your high-scores, and this becomes a much more positive game.
Nevertheless, good fun! I had Typing of the Dead for Dreamcast with a keyboard and played the crap out of that. Even more so than the regular House of the Dead which I also had.
To make my life more interesting, I tried making a bot to play a game. I noticed the game ignores wrong keystrokes and there is no penalty.
So my bot cyclically types the letters A through Z at a few hundred keys per second. It really does the trick!
That extension should have an option for disabling shortcuts for the current tab.