How can the judges be sure the game was made in three hours, and not more? Thanks!
We don't really check as the goal of the jam is to help you make a game. You can submit even if it took you the whole weekend to make your submission! (When submitting, there is a field asking how long it took you)
Another reason we don't check is because there isn't really an incentive to lie about it, there's no prizes (or judges, everyone who participated can vote). The only "reward" for making your game in 3 hours or less, as far as we are concerned, is eligibility to enter the Hall of Fame. But the fact that you made a game is, IMO, a better reward :)
3 out of 72 is too big a margin for trust.
I would prefer a weekly 12 hour jam with limits better enforced? DTJ36 is only monthly.
I tried trijam once. Left it to the last minute, and had some doodles ready so probably only deserved about 2 hours of coding time. Thinking of something achievable in that time, takes too long to plan. As I recall the jam ended before I expected, but the amount of rubbish that would be submitted if the 3 hour limit was strictly enforced makes me suspect people are not entirely "accurate" with themselves.