I do not think that steam played a role in that, it was just because of the halving.
Steam did not added something to the price that was back in the days at 700 dollar, I'm pretty sure about that.
sure steam accepting bitcoin have nothing to do with the price rising before halving occur,it was actually because of halving but the price rising right before halving occur so after halving there's none price rising,but i can sure that steam not yet implement bitcoin at that time