(This is pretty long, so get ready).
There’s actually a very complicated logic to the scoring system — it doesn’t care about whether or not you actually play the buttons shown, only if your button presses are timed to a dot (it needs to be like this to allow for freestyling).
In fact, that’s something to know for all 3 Parappa games — the buttons you actually play are largely irrelevant. What the games care about is whether you timed them correctly.
Some key points for Parappa:
- Every button press timed to a dot is worth 3 points.
- Every button press which is mistimed (ie. between a dot) will cost you points equal to the number of buttons on the original line (ie. if there are 3 buttons on the line, a mistimed press costs you 3 points).
- Any button you press which isn’t on the original line and makes Parappa go ‘oops!’ is worth nothing. It gives and costs no points.
- Any line which scores at least 1 point is Good. Any line which scores no points or loses points is Bad.
- In order for any line to be worth any points at all, you must use and time every unique input at least once (ie. if Triangle, Circle and R appear in the line, you have to play and time all 3 buttons at least once correctly).
- If the first button you played doesn’t match the first button the teacher has, the game will dock some points. Apart from that, the buttons you play are irrelevant. For instance, if the line goes LLR (9 points), and I play LRL, that’s still fine and I get 9 points. If I play RLL, I would only gain 6 points (9 points for 3 timed presses, minus 3) because my first button didn’t match the teacher’s.
Where things get more complicated is when the game tries to determine if your line has good rhythm or not. There’s 16 dots in a line, and once you’ve played a line, the game looks at all your timed presses (only your timed ones, mistimed ones aren’t used) and separates then into pairs (16 dots makes 8 pairs a line).
There’s 4 pairs: a dot and an input (.X), an input and a dot (X.), two dots (..) and two inputs (XX).
If you have at least two of the pairs that aren’t just two dots, the game gives you bonus points. Every .X is worth 15, every X. is worth 6, every XX is worth 9. Additionally, if all four pairs are used in a line, you get 18 more points.
For example: ‘RR.RR.R.........’ In pairs, that’s RR, .R, R., R., .., .., .., ..
That line is worth in total... 69 points (15 points for the 5 timed buttons presses + 9 for the RR + 15 for the .R + 12 for the two R. pairs + 0 for the 4 .. pairs + 18 for all pairs being present at least once).
By the way, if the first button you pressed isn’t the same as the teacher’s, you don’t get any of these bonus points at all. So... make sure you do that.
The long and short answer is that Parappa’s scoring system makes sense, but it’s pretty complicated and knowing it doesn’t make the game too much easier.
When it comes to simply beating a stage, the only requirement is that your rank is Good or above. Points don’t matter, and it doesn’t matter how well you were playing beforehand, if you fall rank in the last two lines, you fail. Conversely, if you play horribly, but manage to scrap a Good rank at the last two lines, the game is fine with it.
Fail conditions are ending a stage in Bad or Awful. Additionally, if you play two consecutive lines in Awful, the game fails you right then and there.
This information is more so useful if you’re trying to get Cool, but I hope this helps.