Emirikol
Adventurer
The store put a vote of the three systems on social media 24 hours ago. So far only three people have voted (all for D&D).
To me it doesn't seem like there's enough interest to even start doing a game, regardless of system. (If folks won't even click a Like button, I don't see them coming to the store and committing to play a game for a few hours.)
My gaming group has a rule: we game as long as 3 will be there. Now, with new players you've got about a 50% show rate, so advertise longer and plan for 2 and grow from there.
We discussed this during our ALIEN RPG group at the game store yesterday. We all agreed its a tough sell to get random groups together with anything other than dnd.
In order to get the ALIEN RPG group together it took a month of advertising on Facebook events and also at the store..and its summer, when nobody wants to give up their weekends!
Good luck.