Also do keep in mind, that a use case doesn't necessarily have to involve Steem. It can be any plausible and feasible use for the Byteball platform, applied to some real world problem or need. So to cut it short, the contest is mainly of creativity, innovation and potentially introducing a use case, that you could profit from yourself. Anything goes, as long as your use case is feasible and the judges can see the potential in the project and it's moving forward :-)

Also - there is no deadline for entering the contest. Anyone can enter by paying the entry fee of 25 MB from their publicly Steem attested wallet.