There is a way to tell if you actually played the game to get the prize.
You make sure you enter, that is the first thing, of course. You can do that during the week while the voting is going on or you can go to the communal contest page, itself and click on the bar that says to register.
It will say 'Participate in the challenge to win.'
Then go to the game in the ARCADE, do not go to the tournament arena, it does not register the games you play in Tourney.
Play at least one game, doesn't matter which level, either
All that matters is if you play. You can play as often as you wish or you can play one game. Even if you don't finish; as long as you gain some points or earn some Kinzcash it logs it onto your account as having been played.
DON'T wait until the bar is already full
When that bar flares up it is too late.
Go BACK to the communal challenge and LOOK at the caption. If you have successfully registered it will say 'You are entered into the competition.' Then you know you will win the prize if the challenge is successfully completed.