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Games that try to simulate real-world activities (like driving vehicles or living the life of someone else) with as much realism as possible. Simulators generally require more study and orientation than arcade games, and the best simulators are also educational.

Games with a distinctive mood, with themes of romance, mystery, or nostalgia

Set in a fictional universe, often (but not always) with fantastic or supernatural elements, alternate worlds, magic and monsters.

Utilizing content created by algorithms rather than human made content. Often utilizes a "seed," a relatively small string that is used to control the randomization algorithm that generates the entire world.

Near infinitely replayable games that usually feature, random generation, perma-death, and brutal difficulty. 

Games that can be played alone