Spacetime Level Generation and Editing with Constraints from Examples

Abstract

When generating levels for tile- and turn-based 2D games, generating a solution along with the level can ensure that the level is completable. One approach is to represent the level and solution as a 3D spacetime block with two spatial dimensions and one time dimension. Recent work in Space-Time WaveFunctionCollapse (STWFC) explored learning to generate such levels with solutions from example blocks by adapting 3D WaveFunctionCollapse for two spatial and one temporal dimension. While this generated solvable levels, the approach was found to be slow and could violate global constraints such as having a single player. Thus, in this work we explore learning to spacetime generate levels with solutions from examples by applying an existing 2D constraint-based level generation system. Rather than extending the 2D generator to 3D, we encode the time dimension in 2D by using a filmstrip representation where each frame represents a step in the time dimension. We compare STWFC and two filmstrip-based approaches: block constraints across frames that are analogous to those of STWFC, and constraints based on differences between frames. We demonstrate an application for interactive spacetime editing of levels and their solutions in the filmstrip representation, along with generating variations of levels sharing the same solution path, and variations of levels whose solution goes through the same arrangement of tiles at a point in time.