Idea for video game.. is it possible...?

i have an idea for a video game, it could potentially be a big hit. but would it even be possible to do? here is my idea..

it will be a free rome game, it will probably be best to set it in the western times. think of a mix between red dead redemption, fallout, GTA, the sims and world of war craft.. . like WOW you make a charicter, level up, u can kill/ steal. everything is interactive and everything has consequences...

this is where my idea is different than most, remember the mlb game that offered 1million dollars to the first person who pitched a perfect game? well like that this will have one main goal. the creator of the game will hide 1 item (or more) in the large world of play.. every 2 weeks the players will get a hint to where the item(s) are.(u could get a entire year of clues and still not find it) your objective is to find it, and take it to a designated spot. first one there wins a set amount of money.. but the catch is when ever it is found a message to all players will be sent out letting everyone know the gamer tag of who found it.. and all the other players if they find you, can rob you or kill u and steal it.

only the person with the item knows where the end marker is to drop the item off. tat way no one can wait for u at the end.. to make it more challenging u get a set amount of lifes per day and if u kill someone the AI "police" will track u down.. so u need to use stealth against computer players and real players.

i also think it would be cool to have the game set where even if the console is off, ur player is still in the game (everyone could rent apts or own houses or be homless.. so u could potentially be robbed while ur not online).. but u can upgrade your safe house with security cameras to seee where the robbers went after leaving the house and gaurd dogs and stuff.

i want the map to be so big it could take a few days to go from one side of the map to the other. at any point u can hide the item anywhere, bury it or wat ever and come back later to get it. who ever gets to the end first wins the money.

thats the short version lol, do u think it would be to hard to create a game that is that big and interactive? wit realistic graphics? i think it could be the biggest game ever, wat do u all think