The unlockable bonus round is one common thing that can be found at all bonus screen games. Most of the times luck or chance is needed to play these bonus rounds. Free spins are often featured when playing a bonus round and this is about chance not skill.

Games are sometimes featured at the bonus round. Once again skill has nothing to do with it as the player has to choose from a couple of contestants may these be animals, cowboys or idols which compete against an adversary. Or depending on the case the player's choice may reveal a prize.

The skill slots are something that can be found in casinos. Unlike the games mentioned above in these games skill is required on top of chance. A game I've experienced was where the player had to shoot some rising balloons with the mouse. It was a game of skill but a game that didn't produced any satisfaction for the player as the balloons moved to fast.

The ideal bonus game is when players actually win some credits after they played the game. The best example is the former Card Sharks slot game, now called The Sharks slot produced by Realtime Gaming.

In this game the player has to guess if the value of the card will be lower of higher from the card turned faced up. After three consecutive right guesses the bonus game is over, as well as after one wrong guess. Fun is the number one ingredient these simple bonus games bring, but unfortunately they aren't found to often in a casino.