Some notes:

• Due to the small time frame for typing, the eyes always have to be pointed to the right of the screen. It would have been nicer to put the characters in the middle. This feels a bit awkward currently. Same for the timer, and if it were a (progress)bar, it would also be "readable" while typing.
• Screw ups are not recognizable (fast) enough: if you type one letter wrong, changing the characters takes to long and in the meantime you can already type another wrong letter, leading to another screw up
• It's very easy to accidentally skip the end screen
• The game would be more fun if you had to type real words, not random combinations