/goal I want to build a typing practice web app for kids. 
At the bottom of the screen are 9 keys representing the positions of 10 fingers, with the thumbs sharing a wider spacebar key that takes up two slots. 
Above those 9 keys is a gradient-transparent rectangle. 
Letters fall down from the top toward that rectangle, aligned to their matching key positions. 
Press the right key as the letter enters the zone and it counts as a hit, triggering a hit effect. 
Consecutive correct hits build up increasingly dramatic effects. 
The falling speed gradually increases. 
At the top of the screen is a scoreboard that adds 1 point for each hit, with a pop animation. 
The whole thing should feel exciting and dopamine-triggering, with plenty of visual encouragement.