Thanks to Panem Propaganda, Quarterquell.org, and Jabberjays.net, we have a solution to the rebels' riddle.
- Go to the One Panem page on TheCapitol.PN.
- Click the diamond arrow symbol.
- Type in OLTM or that good ol' Konami Code (UP UP DOWN DOWN LEFT RIGHT LEFT RIGHT B A)
You will get this screen, which teases there is something to come tomorrow.
"Today we assemble, tomorrow we will rise."