The problem with Runescape's combat system is that it's so clunky and awkward that any attempt to do anything interesting or novel with it in eg. quests just becomes a source of frustration because all the responses are delayed
@joepie91 I've been playing Ultima Online recently and while it's outdated as hell, I find its combat system to be pretty unique. I can get health bars of every opponent and choose between them at a whim. Unfortunately, it is missing the crucial bit of information of which enemy you're actually fighting, but it's a neat idea that I think should be looked at by more games that don't do target locking or tab targeting.
@joepie91 in this picture, I can see the health of everything I'm fighting, and switching targets is as simple as double clicking their healthbar. It's a bit close to Final Fantasy XIV, which has an automatically generated "emnity" list you can choose mobs from.
As much as I wished RuneScape could be a successful to Ultima Online, its combat has always fallen short in my mind. Even with the leveling constraint (Ultima Online only lets you max six skills), I still think I prefer Ultima Online to RuneScape, and in general I think every MMO dev should play it to learn what their MMO can do to improve.
Like, I appreciate the desire to experiment with character switching in combat, but uh, maybe you should make sure it's possible to reliably target opponents first?