Logical puzzles can support teaching informatics and rational thinking. We have developed a metamodel-based approach that supports development, configuration, and automatic construction of puzzles with a syntax close to predicate logic and OCL and a semantics close to UML object models. We extend this approach by introducing puzzle metrics expressed with OCL that consider puzzle complexity w.r.t. syntactic and semantic aspects. The aim of developing the metrics is to tune the logical puzzles for novice and expert players and learners. We regard the approach as an ideal case for demonstrating the flexibility and power of OCL due to applications of OCL for various purposes and on different modeling levels.