Not bad at all and the only challenge after completing the game and all the medals is to see how fast you can put in the character names afterwards.
The gameplay seems easy enough in that you guess the hero names but they have to be in all lowercase with no additional spaces or anything like that. The only names I imagine people might have trouble getting right are the following:
Reinhardt / reinhardt (I spelled it as reinherdt the first time for some reason)
Torbjorn / torbjorn (Is actually Torbjörn but for the sake of time, no fancy O is needed)
Symmetra / symmetra (I kept tripping up the first couple of times and putting in two Ts instead of two Ms)
There is only one thing I could think of to improve this game in regards to completion time. Instead of having players having to click on the textbox each time to put in a hero name; it should instead just already be ready for the player to input the name which would probably trim off 10-15 seconds overall for really fast typers.
That being said, I did replay the game a couple of times until I was able to reach the top 10 scores at the time of this review. I imagine if I had not messed up on Symmetra and Reinhardt's names a couple of times, probably could have got to the top 5 with a final score of around 810 which is hard to do. The reason being that when you get all the names written each time, you only get 30 seconds added onto the timer.
Overall, pretty fun and challenging in regards to trying to see how many names you can type in time. I would just make it so you do not have to click on the textbox since that kind of takes away a second or two that the player could be typing.