The impossible badge took a bit less than three days but the issue is the fact that it REALLY doesn't want to award itself. I've finished the game but it's still stuck at 17.
THE 12 KIDS:
2 are in the world map, search them out.
One is in the training, upgrade it enough.
One is in the shop, over the tent i think.
FOUR in the museum. As you get in the main hall, there is one under the table and one near your money counter.
One in the armory, scroll faaar right and then down.
One is in the statues, look in the window up there.
Two are in the arena.
One is over the sign that says "Choose a battle"
Then, go to battle 1 and look at the wooden sign. There is a kid hidden there.
One in the hero screen, near the thing that the player stays on.
Three are in the house. One is in the woods, one near the barrels and One in the windmill
[+] to keep this alive!!