Spheres (2009) was a 1v1 arena game made in Game Maker for a gaming cabinet. It was one of the first games I made myself, and was made for the “arcade machine” we had at school, featuring a joystick and three buttons per player.
In Spheres, one player played as the Builder with the ability to build defensive turrets, as well as having an energy shield. The other player played the Wrecker, wielding a machine gun and a healing ability.
The goal was to get higher score than the opponent, but only the player controlling the Builder would get score every second they survived. The players took turn playing the Builder, and after that a winner was declared.
During my lectures and presentations over the years, this game has always been brought up in an example where balance could make or break a game. In the example, the balancing of the healing ability was brought up – where on one iteration it was a short “full heal”, and on the other iteration it was a slower regeneration ability.
When playtesting, the example shows how playstyles differed between the two healing abilities – when it was a full heal the Wrecker players hid behind cover and used a “cover shooter” playstyle. But, in the regeneration version players activated the heal as the first step of an attack. The heal started, and they aggressively charged the other player. When the heal was about to end, they instead covered and took a defensive stance until the ability could be used again.