Thanks !
After you touch the lever, the cannon ball appears near at the right, so when you take it you go back to the boat area ( I think is what you call the menu I think it's the worst part of my game) but now you have cannon ball to shoot ( with right click and change size of the shoot with left or right arrow) and to destroy rocks, to have access to the chest and it's the end, with a simple victory screen.
The problem is that I give up all the UI part so because of that there is confusions about what to do and what happen in the game, and i coul'd put a sound effect on the loot of the cannon ball too.
Thank's for the review !