The implementation confuses me though.
It's not clear at first that all "games" (though I would think it's rounds of a single game, not distinct games) are available rather than this being some kind of daily challenge.
The instructions are very drawn out and repetitive. There's no reason the Welcome, Background, and Rules couldn't be on one screen. The Mission page should just be merged with Rules.
The time limit seems pointless given that you get to see the text before the game starts. You could just write your text in Notepad using as much time as you want. I would either get rid of the timer (greatly preferred) or stop showing the text in advance (if you must).
It's not clear what other rules (AI?) are being used to judge whether a response is valid, so when you get marked invalid even though you're using all the required terms, it's not clear what you're supposed to do to make it valid.
It would be nice to be able to review the Background section of the instructions while writing.
After completion, you see your response compared to a target, but you can't see the original anymore to compare target vs original to see how the target improved on the original.