Contribution: This article presents the design of in-game tools to support learning within an educational video game and investigates the impact of tool usage on engineering students' performance in an introductory digital circuit design course. Background: Despite the level of appeal of video games to college students, there is a lack of empirical evidence of how to design effective games to address educational goals. One component of games that can serve as a support mechanism to help players be successful in the game is the in-game tools. This article investigates the impact of three types of instructional in-game tools on engineering students' performance on digital circuit design tasks. Research Questions: To what extent do different types of in-game tools (content-specific instructional guidance tool, scaffold, and productivity tool) contribute to players' performance on digital circuit design tasks? Methodology: This article presents the design of an educational video game to teach digital circuits design. It presents three discrete types of in-game tools and investigates their impact on students' learning performance. For this investigation, multiple regression analysis was used to show the relations between the tools and learning performance (N=176). Findings: The results show the player use of tools that provide content-specific instructional guidance and scaffolding for troubleshooting is correlated with their learning performance. The productivity tool did not significantly contribute to the learning performance of the students.