I was thinking about computer games where you control a party of heroes.
One of the things I always felt was difficult about these systems is balancing status effects. Status effects always felt extraordinarily irritating to me. All of them. I've never seen a status effect I thought made the game more interesting, with the exception of reflect.
The core problem with status effects is that they are essentially time fees. They force you to spend precious actions fixing them. There's not much difference between being turned to stone, blinded, stunned, paralyzed, KOed, killed, berserked, charmed, confused, muted, toaded, etc. If they have any effect at all, they basically make that character useless until you spend time fixing that character. So they "drain" your action time until you "spend" some action time to fix them.
Sure, they vary in details. They can be healed in various ways, and some are "high-functioning" states (such as berserking a warrior), but the details don't really make them feel interesting to me. When I run into a status-effecting enemy, the basic thought is "how fucking irritating. I'm going to spend half this battle treating status effects rather than fighting."
So... how can you make a status-effect-ridden RPG interesting?
Change how time works!
Every phase (no turns, just phases) you can command only one hero to take an action. This uses up all her action points. The more action points she has, the more powerful her attacks are (and perhaps the more high-level attacks open up).
Every phase, every hero gains an action point - two, if they are not available to be commanded due to an enemy-inflicted status effect.
Battles are longer, and multi-phased. Rather than distinct random encounters, you would face an unending trickle of enemies as you explore, push through, and defend positions. Action points carry over throughout this.
So if a character is, say, swallowed by a fifteen-foot slime monster, that character cannot take any actions. But that's not so crippling: you can only make one character take an action per round, anyway. While he's incapacitated, he's gaining action points at twice the normal rate. So when you kill the slime, he's freed and now has a bank of action points that make his next attack ten times as strong as normal.
Of course, you can also do ongoing attacks. The warrior might be told to attack a skeleton knight. It's not just a one-shot attack, but an ongoing fight where damage is dealt every phase. The warrior gains no action points while he does this, but it deals ongoing damage and keeps the skeleton knight busy...
Straightforward and, I think, probably kind of fun.