In the big city, folk'll learn at them big schools how to do magic with wands and whatnot. And that's fine for them as have the money to go to the big schools. 

Out here, folk with a lick of magical talent can't afford to study, so they take shortcuts... turns out a gun has just the right properties to enhance basic evocation. 

Y'all might not be as fancy as them city mages, but when demons come to claim the town, ain't nobody gonna think any less of you then. 

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Gun Mage is a one-page story game about using firearm-fueled magic to take on a wave of demons. The setting is vaguely Wild-West-themed, but you can adapt it for any situation in which minor magic users face overwhelming odds.