I want to suggest you develop a coaching mode for bowling and additional Steam achievements for this:
Intentionally aiming for different groups of pins to knock down, different scores to achieve over a few frames and a timed mode to get the highest score in 30 minutes of consecutive bowling.
I’d also suggest the game gives a target score to reach after the 4th frame. Base this partly on other games bowled that day, during the past few days and the average score of bowling.