Good stuff :D
Really nice idea and fun to play. The difficulty is about right for a 20 second game but, as Xeno mentioned, the selection of danger zones can seem unfair at time so a little balancing could help.
The execution is very good and could benefit from having some audio. Keyboard clacking noises would help to sell the idea.
I can see various ways this game could be extended into something bigger after the jam and that's a very good thing. Things like bonus points if you manage to spell out a given word while you're under attack. Or a 'bug teaches typing' mode where you play as the attacker.