  Many advancements have been made in procedural content generation for games,
and with mixed-initiative co-creativity, have the potential for great benefits
to human designers. However, co-creative systems for game generation are
typically limited to specific genres, rules, or games, limiting the creativity
of the designer. We seek to model games abstractly enough to apply to any
genre, focusing on designing game systems and mechanics, and create a
controllable, co-creative agent that can collaborate on these designs. We
present a model of games using state-machine-like components and resource
flows, a set of controllable metrics, a design evaluator simulating
playthroughs with these metrics, and an evolutionary design balancer and
generator. We find this system to be both able to express a wide range of games
and able to be human-controllable for future co-creative applications.
