In the first half of the 80's, the developers started adding level editors to their games (Lode Runner, Excitebike, Mind Strike, and others). They are based on the philosophy of the intervention, where the player acts not as a passive gameplay participant (who takes action, but is also limited by certain boundaries), but as an absolute creator, the architect of game reality. Nowadays, when game development is accessible as never before, and fan content weighs a lot, official game editors and SDKs are not a surprise. Often they offer an effective tool for creating own levels, distinctive and authentic. However, the point of custom levels is that they, unlike mods, expand the already available mechanics or put them at a different angle. Sometimes such editors exist separately from the game, which allows players to explore the mechanics way deeply, vanishing borders between custom levels and mods. If video games could be art, then the fan levels may have an artistic value, too. ...