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Rathenn and Launchpad

Rathenn is an under-development 2D platformer game that tightly integrates procedural content generation (PCG) into the game’s mechanics and aesthetics. Mechanics-wise, Rathenn is consciously positioned within the tradition of the platformer. The basic actions available to the player are those typical of existing platformers, including jumping over gaps, killing enemies, avoiding stompers, and climbing ladders. The game consists of a series of level segments connected by ladders; level segments are generated at play-time at the end of a climbed ladder. A key aesthetic in Rathenn is that of discovery: the player is encouraged to explore both the physical space of the level and the generative space of the procedural level generator through climbing ladders. Each ladder is color-coded, and each color influences the generator in different directions. For example, climbing a red ladder will increase the frequency of enemies appearing in the level, or climbing a purple ladder increases the avatar’s movement speed and jump velocity. The first iteration of the game is available online.

Rathenn uses the Launchpad AI system (Smith et al 2011), which is a rhythm-based level generator for 2D platformers that are characterized by dexterity challenges. The rhythm-based approach is based on observations (Nicollet 2004, Bleszinski 2000, Kremers 2009 pp. 263 – 267) that rhythm and pacing are deliberately designed and crucial to challenge in this kind of game. Launchpad allows a designer to refine its generative space by manipulating parameters that have a clear and intuitive impact on generated levels. These parameters dictate a general path that the level should take, the types and frequencies of geometry components, and how collectible items are distributed throughout the level. Adjusting these parameters can drastically alter the generated level.

Rathenn is currently in its second iteration on both the game and AI system: there is now a concept of tiered level generation, which monitors the player’s progress along a path and provides more challenging level elements as the player improves. For example, the player will first encounter spikes, then moving enemies, and finally flying enemies as they progress down the “enemies” path in the generative space. This addition requires changes to both the game design and the AI system. There is also now a story to the game, determined from the affordances of procedural level generation. The game is set in a dreamscape, and the player is striving to overcome different fears characterized by the various types of challenges the game can provide.

Gillian Smith, April 2011

Bleszinski, C. (2000). The art and science of level design. [Online]. Available: http://www.cliffyb.com/art-sci-ld.html.Kremers, R. (2009). Level Design: Concept, Theory, and Practice. Peters/CRC Press.

Nicollet, V. (2004). Difficulty in dexterity-based platform gamesGameDev.net. [Online]. Available: http://www.gamedev.net/reference/design/features/platformdiff.

Smith, G., Whitehead, J., Mateas, Michael, & Treanor, M. (2011). Launchpad: A Rhythm-Based Level Generator for 2D Platformers. IEEE Transactions on Computational Intelligence and AI in Games3(1), 1-16.

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