Most game now have "micro transactions". I have not followed closely but I guess that your start the game without all the characters unlocked, so you need to pl

Most game now have "micro transactions". I have not followed closely but I guess that your start the game without all the characters unlocked, so you need to play X hours of time to unlock that character, or buy it in addition to the base game to unlock it immediately. Which might be a bit steep after you've just spent $80. edit: so after reading minimaxir links it seems you can not pay to unlock a new character, but since you have to effectively chose spending your credits (i.e time spent playing) either on improvement like weapons or new characters, it greatly incentivizes you buy in-game currency.