They all take skill. It's just that games have a certain element of randomness, diminishing returns, and feedback loops. With a low randomness, a more skilled player will win 99% of the time (the chess area). With a high randomness, a skilled player will win 51% of the time (More in the Mario Party area). A game with more randomness will feel like it has less skill, because the payoff for skill is less pronounced. This is compounded by diminishing returns, where after a certain level of proficiency, your odds of winning stop increasing dramatically. You still improve your odds, but not by much. Also, many games have negative feedback loops where a person who is far ahead is hindered, and a person who is behind is helped (Think Blue Shell/ Bullet power up in Mario Cart). This levels the playing field even more, and makes a game feel less skill focused. However, unless it's a solved game, then any amount of skill must still be improving your game. It just might not be by an appreciable amount.