What did Scrooge do while his nephew and the others were playing games?

Scrooge played along....

There might have been twenty people there, young and old, but they all played, and so did Scrooge, for, wholly forgetting the interest he had in what was going on, that his voice made no sound in their ears, he sometimes came out with his guess quite loud, and very often guessed quite right, too; for the sharpest needle, best Whitechapel, warranted not to cut in the eye, was not sharper than Scrooge; blunt as he took it in his head to be.