It's hard to tell how many missions are available because you can go back and forth through the game without caring about story progression.
There are variable numbers of missions in the game, depending on the player's path and decisions made. The player can ignore main story fragments; take shorter routes; do fewer side tasks; cheat to complete tasks; avoid violence (and skip many sub-missions); or use ferry service, bike, or car - We have over 151 missions for you to enjoy this game.