Drawn circles involved in ritual magic, often inscribed with various geometric shapes and runes.
Alternate name: Summoning circles
The first video game about Magic circles was released on June 1, 1994.
id Software has published all these games
Drawn to ground with chalk or salt, though even plain stick drawing is supposedly enough. Anime/manga and with them many others have popularized the magic circle on demand type where the magic circles appear as part of the magic (eyecandy) rather than being made before the magic can be done at all (ritual magic).