That's awesome, it's always great to have more games of this style! The grading is different for each wound, but I made a whole Tumblr post about the suture grading here: https://giddydelphiresearcher.tumblr.com/post/772349210800619520/suture-grading-...
Examples of some other grading rules: For objects extracted with forceps, a COOL is awarded for being fast enough, a GOOD is given if you're slow, and a BAD is given if you ever dropped it. For excising Nous, it gives a BAD if you made any tumors detonate, and a COOL otherwise. And for burns and Powell Procedure tumors, they always give a COOL when you put gel on the membrane, just to say "good job for completing that long process".
I'll probably go back and add more grading rules when I finally add a proper score system. There's a lot to consider there.