I'm assuming there is a better ending when you rescue them all. I'm guessing the board will show just 300. I'll have to try that, nice find mate
EDIT: I dug it up, for people who play on PC, the save files are avaliale from several websites.
300 Dead --> All mudokons killed!!! Note that you can't get this
ending normally (you need to save some mudokons to
make your way through the game). Slightly different
to "bad end" (300 mudokons killed).
Save all --> All mudokons saved. The game shows you some pictures
not included in the "good end" (300 mudokons saved).
Bad ending --> You didn't save enough mudokons. Sorry, you will pay
this crime (140 mudokons saved).
Good ending --> Congratulations! You saved most of your friends!
Your quest has ended happily (241 mudokons saved).