Steambirds: Survival Mobile

https://lostgarden.home.blog/2011/10/13/steambirds-survival-mobile/

arrow of play game analysis choice pacing goals

An introduction to the concept of arrow of play, the property of systems that always move the player forward (such as hunger in roguelikes). Several examples from Steambirds about arrow of play: decay, increasing enemies, short-term and long-term goals, currency and currency flow, and limited choices.