Build a game for both Android & iOS

Scavenger Hunts:
(Goose Chase is an App that allows for this kind of game function). I don't want people to be able to create their own games (like they do), but I'd like to have the end result that their App produces.

-Users can choose from a number of games
-DIY Adventures
-City Wide Adventures
-Camp Adventures

Hunts include:
Questions that require right answer
Upload of video
Upload of photos
GPS?
Points for each challenge

Adventures can:
-show points scoreboard
-create slide show of photos and videos at the end of the game
-ability for participants to share photos on social