The Advantages of Binary Health For Combat

In the real world, injuries weaken people. A healthy soldier is more capable than a wounded one. In most games with HP and damage systems, however, health is binary. TCG players like to say, "The only life point that matters is the last one." Units act at full strength until they die. There are some exceptions, but most games follow this pattern. So what makes binary health systems so popular? Simplicity is part of it, but the deeper reason is that greater contrast between life and death makes combat more exciting.

If ability scales with health, then using weakened units is boring. In Heroscape, the number of actions a squad gets depends on how many figures it has. This creates a degenerative health dynamic in which squads weaken as members die. If you have four Blade Gruts, you have four attacks. If you have only one left, you have one attack. Weakened squads are barely worth activating, so players field at least two copies to have spares. By contrast, with binary health you feel urgency to maximize a wounded unit's value before it dies.

On the other side, attacking a unit with binary health is more exciting because of the contrast between dead and alive. Killing a binary health unit yields a much greater reward than merely damaging it because it prevents it from acting. If units weaken as they take damage, then killing is not much better than damaging since either case impairs their ability to act.

My game Junkernauts does not use a fully binary health system. Your bots' HP is their attached tools, and as they take damage, they lose tools and become weaker. However, it was even worse before: an earlier version tied attack strength to tools as well. A bot with one tool rolled one die. Even if you failed to kill your target, you could mostly ignore it. When I realized the problem, I changed combat so bots roll the same number of dice regardless of how many tools they have. Now even a severely injured bot is still a threat.

If you want to design a degradative health system, be sure you know why you are doing it. There are good reasons why most games do not weaken injured units. In general, combat games should default to binary health as it leads to more urgent and exciting combat.