Picture this: you are a remnant of a civilization on its way out, after years of prosperity. The advancement of old has been replaced with flesh-eating zombos, ready to pounce at a moments notice. Like any other day, however, your pet needs to use the bathroom and get exercise so they don't tear apart all 0f the furniture.
With the actual purchase in the future you can likely expect (given met time and budget requirements instead of zero):
a twin stick arcade shooter with a unique mechanic and a tight arcade loop at a sawbuck price.
More pet selection
Varied gameplay and enemy ai
More variation to procedural generation
Multiplayer
Pet, player, and enemy animations that don't detract from the style
Working online high-score system WITHIN STEAM RATHER THAN RUNNING THE EXECUTABLE YOU DOWNLOAD WITHIN STEAM OUTSIDE OF STEAM TO GET IT TO WORK.