Liked the bugs, they're funny! Answered all questions correctly (unlike the cars example above, lot more familiar with computers). Very clean design. At the final screen it says "4 question" correctly. You probably want to change that to "questions".
Timer adds some urgency to a quiz. On the other hand, you as a learner, don't control the duration. Some learners literally get anxious when there's a timer (we got this feedback a lot times). One thing you can do is let the learner set their "confidence level" before each question. The more confident they have, the less time is given (but within a range that is achievable). What you see is that less competitive learners start out with low confidence and gradually move up but they still enjoy the game. To compensate for the time allowed for each question, you can introduce the "star" method (like in Cut the Rope). You'll pass a question as long as you answer correctly but you can get a one, two or three star for each depending on your confidence level. At the end, you can give the average star rating. Some learners go back and redo it again just to get more stars :)