If by fast you're referring to the controls, that's because they mimic more modern games like tetr.io or jstris. You can change the controls to be slower in the settings if you prefer it that way.
The values the game uses for gravity can be found here. Most guideline games use these, but many games differ on how pieces lock when they reach the bottom. In some games like Tetris DS, pieces never lock if you continue rotating. This makes the game way more forgiving. I chose to go with move reset, like most Tetris games.
I'd like if the game had a bit of character, and adding a ton of options that change the rules feels like it would ruin that.
To be fair, the game is more tailored for modern/guideline Tetris fans as the GBA already had great "classic" Tetris games. If you like playing those I can see how my game feels too fast, but if you stick with it you might not be able to go back :)
Anyway, thanks for the feedback!