[z3t4]

My experience is that almost 100% do sign up. Signing up is not a barrier. Funny statistic I had in a game was that while almost 100% did sign up, only 50% of those entered the game. After highlighting the "enter game" button, that 50% went up to something like 85%. But the takeaway is that almost everyone do signup almost automatically.

[karmakaze]

Do an A/B test, and see how many enter the game when presented with a sign up form vs without.