Digital systems offer computational power and instant feedback. Game designers are using these features to create scaffolding tools to reduce player frustration. However, researchers are finding some unexpected effects of scaffolding on strategy development and problem-solving behaviors. We used a digital Sudoku game named "Professor Sudoku" to classify built-in critical features, frustration control and demonstration scaffolds, and to investigate their effects on player/learner behaviors. Our data indicate that scaffolding support increased the level at which puzzles could be solved, and decreased frustration resulting from excessive numbers of retries. However, it also reduced the number of unassisted placements (i.e., independently filled cells), and increased reliance on scaffolding tools, both of which are considered disadvantageous for learning. Among the three scaffold types, frustration control reduced the potential for players to feel stuck at certain levels, but also reduced the frequency of use of critical feature-making tools, which are thought to have greater heuristic value. We conclude that the simultaneous provision of critical feature and frustration control scaffolds may increase player reliance on available support, thereby reducing learning opportunities. Providing players with critical features and demonstration scaffolds at the same time increases reliance on available support for some players, but for most it encourages the development of solving strategies. (Contains 5 tables and 5 figures.)