The computer science (CS) unplugged approach intends to teach CS concepts and computational thinking skills without employing any digital tools. The current study conducted a systematic literature review to analyze research studies that conducted investigations related to implementations of CS unplugged activities. A systematic review procedure was developed and applied to detect and subsequently review relevant research studies published from 2010 to 2019. It was found that 55 research studies (17 articles + 38 conference proceedings) satisfied the inclusion criteria for the analysis. These research studies were then examined with regard to their demographic characteristics, research methodologies, research results, and main findings. It was found that the unplugged approach was realized and utilized differently among researchers. The majority of the studies used the CS unplugged term when referring to "paper-pencil activities," "problem solving," "storytelling," "games," "tangible programming," and even "robotics."