Often, if the skill is being used in a common or practical way, people will consider it a craft instead of art.
Art & Portfolio
Likewise, if the skill is being used in a commercial or industrial way, it may be considered commercial art instead of fine art.
An art form is the specific shape, or quality an artistic expression takes.
Sweets & Books
The formal qualities of video games are non-linearity, interactivity and virtual presence.