I'm making some balancing changes to reduce the amount of corruption on the map and make killing hearts more rewarding (including rewarding assists) and killing hearts directly reduces the spread of corruption.
Reducing the spread seems kind of irrelevant. You make a solid wall of purifiers, or the corruption gets through. The rate of corruption growth doesn't factor into it. The only thing is, if you have enough people and you're fast on a new round, slower growth might let you win the round more quickly by saving the existing uncorrupted space. But even then, if you spend time killing hearts, you give up time you could have spent walling off the uncorrupted space.
That said, it's not entirely clear the rules by which the corruption spreads. Have you played any of the Creeper World games? I'm not saying you should copy them, but it's an example of a reasonably elaborate ruleset leading to reasonably varied player choices, with a similarly amorphous enemy.
Agree on basically all of this
Also it is better to do hearts as you naturally get to them with the purifier line so you can take advantage of the space they clear.
the spread is already so fast it doesnt matter much if it is faster. You have enough time to shave a little corner at the start of a wave or if people are working together a nice little corner, but more likely than not you are going to need to purifier most spaces
I wonder if letting the corruption stack past 3 would make it more dynamic/group based or if it would just make some waves impossible after a period of low participation.
I'd kind of prefer that, but it could get out of hand.
ofc, if it gets out of hand, that just opens the door for new cool powerful solutions as you lvl up
I think I say try letting the corruption stack a Lot higher than 3