Gaminfication with some randomness.

For example a pinball game where you get paid in proportion to your result compared to the players before you.

It will be imortant to find the right balance between skill and randomness. Slots only include luck so people know they can´t beat it long term. Chess only includes skill. A medioker chess player will win every time against a bad one. The bad ones will quickly realize how bad they are and quick. Poker is closer to the right balance between skill and luck. Pros play because they know they can beat the game. Recreationals play because it´s fun and they often overestimate their skill and blame their losses on bad luck. Most recreationals try to improve their game, they have a dream of becoming a pro.