The Secret World had a level-less system which worked very well. Certain skills were required to win against certain enemies (like -regen on a fast-healing creature) so you were gated by ability rather than raw power, which I always considered a very elegant design.
But anyway, I promised Consultant I'd chip in on this weeks ago, but it turned out I had a lot to write and numerous distractions...so rather belatedly, here begins a rather long (and multi-post for ease of reading) discussion on killing things slowly.
The first topic is something I have mentioned before, but for the sake of clarity will cover again. Time-to-Kill, or TtK.
This is quite simply how long it takes you to defeat an enemy. It's important because time
is your fundamental currency in an RPG. You have a limited amount of time, and making the most efficient use of it is thus most players' goal. This is why XP debt is required - it "evens out" high xp gains from harder enemies by slowing xp gains down if you die. That's the "risk" in the risk-vs-reward balance. Any death penalty in any game can be reduced back to costing you "time" - everything is replaceable, but it will cost you time you could have been increasing in power.
Time-to-Kill, the time taken for one character to kill another, also affects how a game feels. I'm going to switch genres a second, and compare two FPS games - Brink and Modern Warfare 2. In Brink it was perfectly possible for a tough character to take an entire sub-machine gun clip and keep on going. The TtK was quite high. Modern Warfare 2 would kill you with a single bullet to the brain - pretty much instant TtK. Thus the games felt very different to play (obviously setting and the parkour mechanics also affect that, but this difference was why I dropped Brink almost immediately despite loving everything else about it).
TtK has to "feel" right with the players' expectations, within the context of the type of game and the setting. As another FPS example, for me The Division didn't feel right. It was just immersion breaking to fire an entire machine gun at an escaped prisoner face and have them still coming at me. In Destiny doing the same thing at an alien is fine, because, well, alien, with superior tech, different biology, etc.
All of that rambling introduction brings me finally to the big question: what is the Time-to-Kill that would feel right for Ship of Heroes, for each type of enemy? And, to connect this with the actual original topic of discussion, how does that change as you level up?
Let's just start with minions, for simplicity. How long should it take a level 1 player to defeat a level 1 minion? In City of Heroes, it was about 10 seconds (using this video
as a reference). That's a nice round number, so let's stick with that (ignoring differences in powers and archetypes, obviously).
How long should it take a level 50 to defeat a level 50 minion? To answer that, consider how different lengths feel to play - if it takes a long time to defeat an enemy, there are two interpretations. One, you're weak, or two, they're strong. We're talking minions, so we can discount the second option. Should you be feeling stronger at level 50 than level 1? Definitely. So to give that feeling, TtK on level 50 minions should actually be quicker. There's an iconic scene from the Birds of Prey comic where Black Canary is working out her shopping list while fighting off a pack of mooks - that level of enemy is so mundane and routine for her now she's literally doing it on automatic. While players shouldn't be bored fighting enemies, they should be able to (at a high level) plough through foot troops easily. So let's say about 3 seconds TtK for an "average" level 50 minion.
At the other end of the spectrum, how long should a giant monster take at level 1? Remember, if it takes a long time to defeat an enemy then either you're weak (you're level 1, sure that's fine) or they're strong (it's a giant monster, so yes again). So we have two reasons for it to be a hard fight. As a counter-balance, the player still has to feel like they're contributing. Each attack has to have a noticeable effect on the health bar (bizarre things like how big the health bar is also affect that - bigger bars mean bigger changes in health for the same attack - but that's outside the scope of this discussion). How long would you feel comfortable fighting a GM for, as a level 1 player before you'd get bored? That's a genuine question - I can't answer that for everyone else, so feel free to chip in on that. It should probably be a community poll question actually.
So now a level 50 player comes along. They are stronger, and they should feel stronger, so they should be able to do more damage to the GM, right? For the same GM, absolutely. The question is - how much more? If the difference is too much, then the level 1 player, even if they felt fine about their performance before, will now reframe it in the light of the level 50's damage and feel useless. But obviously if the difference is too low, then the level 50 player doesn't feel powerful and epic like they should. That sweet spot is something that will just have be tested and played with - math can't solve everything and that's very much one of those questions that'll need a lot of real-world testing to determine.
Why did I bother with all of this if my answer was, "We'll have to test it and see?" Because where that answer lies determines how you scale damage in a mentor (or GM) situation. And that'll be my second post.