The phrase "arcade games" originally referred to coin-operated video games. Video game arcades were popular hangouts in the 1980s, but have since declined in popularity. Subsequently, "arcade" has taken on new meanings.
As modern games
Coin-operated arcade games were designed to be played in short bursts, and were often easy to learn but difficult to master. Modern games with these characteristics are sometimes described as "arcadey" or explicitly termed as "arcade games," even if they were never released in a coin-operated format. For example, Microsoft's digital distribution platform for original games on the Xbox 360 console is called Xbox Live Arcade.
Relationship to casual vs. complex games
"Arcadey" or "arcade-style" are also used to describe games that alter or simplify aspects of real-world activities in favor of a more video game-friendly approach. This approach is often held up as the opposite of strictly realistic simulation. An arcade-style baseball game, for example, might offer fewer innings, unrealistic pitching physics and far more home runs than a simulation game.