Abstract

This work presents a new proposal to evaluate diversity and difficulty aspects of procedurally generated levels in 2D platformer video games, based on the interaction between the level’s structure and the combinations of game mechanics required to complete it. For this purpose, we implemented a level generator inspired by the game Spelunky and a simulator of an intelligent agent capable of navigating platformer levels with physical constraints using an A* algorithm adapted to the genre. We defined 14 different agent profiles with various sets of mechanics restrictions, assigning each one a general restriction weight obtained from simulation results on Super Mario Bros levels. We proposed two metrics: dynamic diversity and dynamic difficulty. The former is calculated as the proportion of the agent profiles that are able to traverse each level divided by the total number of profiles. At the same time, the latter is a weighted sum that combines the proposed dynamic diversity score with the individual restriction score obtained by each agent profile for a given level. Next, we generated 1,000 levels and evaluated each one with all our agents’ profiles, applying our proposed metrics and comparing them against other metrics found in the literature. Our results show that, when the weight of agents’ outcomes is low, the dynamic diversity proposed metric achieves a significant correlation (r > 0.5; p < 0.001), which attenuates as weight increases, indicating that agents’ restrictions capture aspects overlooked by traditional structural metrics. On the other hand, the dynamic difficulty proposed metric shows a low correlation with structural difficulty, especially when grouping levels according to structural parameters, highlighting the importance of incorporating game mechanics restrictions alongside level structure. These findings validate that integrating both aspects, level structure and mechanics restrictions in agent simulation, provides a more comprehensive evaluation of levels, enriching the understanding of how game mechanics influence the design and playability of 2D platform game levels.