I think I’ve figured out a workable system for combat in Corrupted by Ruin. The biggest constraint is that it must be fast and uncomplicated since each hero incursion potentially initiates multiple encounters. Forcing players to go through the same actions many times will get repetitive. The natural model for quick, simple combat is an idle system where the player sets up the battle and lets it play out. Just think of Loop Hero, where the player speeds through hundreds of fights in a run. So I decided to have a similar system, where combatants have health bars and cooldown timers and attack random targets.
Idle combat comes with its flaws. My chief concern was that it would muddy the differences between different monsters, which happens in “Hero’s Hour.” I think I can get around this by limiting the number of combatants on each side to eight, but this still leaves the question of how to distinguish monsters from each other without the ability to select actions. And I think I have found the answer – a variant of my idea to incorporate Spirit Island threshold mechanics, but one that treats monsters and heroes as asynchronous element converters.
Here is how my new system works. Each creature has two or more actions, each with a priority. It goes through its list in order until it finds something it is capable of doing. Each ability may have an elemental cost and might produce some elements. However, these are available to any creature on either side of the fight – for example, the heroic cryomancer might use the water element your slime produced to boost a spell, or your salamander might benefit from the enemy flame knight’s fire generation. Each battle becomes a converter-based economic game.
One implication of this system is that speed matters a lot. If you see a slow hero that needs fire to be effective, you can counter it with a faster monster that also uses fire because it is more likely to get the element first. Or, if there is a quick hero that consumes water, you might avoid using water monsters.
Another neat thing that I can do with this system is to change the behavior of creatures depending on what is available. For example, maybe there is a troll that typically guards other monsters, but if you flood the room with psychic energy, it goes berserk and starts attacking. The player can then use elements to choose a strategy for their side and manipulate their enemies.
One concern with any combat system based around synergies is that players will get locked into a pattern. If a combination of monsters is good, why not just use it every time? I predict that my elemental conversion system will avoid this because even the same team of monsters will behave very differently depending on the enemy heroes they face. Furthermore, even though you fight the same heroes in multiple rooms within a single incursion, the rooms can also consume and produce elements, which should be enough to shake things up.