At playTIcasino, you can increase your Player Level by earning Experience Points. Experience Points are gained every time you wager coins in a game. By increasing your Player Level, you unlock additional Slots Games.
You need to reach the corresponding Level in order to unlock that game. For example, you need to reach Level 5 in order to unlock Spooky House, as per the image below.
You can view your Player Level, as well as your Experience Bar, at the top of every game screen.