Interesting topic! I have some thoughts which I hope I can formulate reasonably coherently despite this being well past midnight and I’m only up because sleep eludes me.
I’ve played quite a lot of this style of game, mainly Diablo 2 and 3 (and some imitators like Torchlight) and Borderlands 1 and 2 (the Pre-Sequel had some annoying areas so I haven’t played that as much).
For me, the fun of the loot aspect of these games is that it encourages mixing up your playing style, a feature that was noted upthread. In Borderlands, trying out a weapon that seems interesting and realizing that that specific combination of characteristics makes it hilariously fun in some siutations and useless in others is a big part of the draw, and finding something in Diablo 3 that enables a completely new build is also interesting.
As a sidenote, many, if not most, MMORPGs have at least some of this even if the emphasis is less on the randomized items in my experience, and for me personally they do it in a much less interesting way where you’re mainly comparing minor bonuses and trying to decide which is slightly more advantageous. That’s even less interesting in a TTRPG, I think, so I’m going to put that up as something to avoid.
Another attraction, as was also mentioned upthread, is the ability to zone out a bit while you’re playing. When I play these games I’m a bit more engaged than when I do extended mining sessions in Minecraft, but not all that much. However, I don’t think this is something we need to emulate in a TTRPG as I think that’s a pleasure specific to the solitary video game experience.
Something I think you do want is the fast and furious pace of combat. You don’t want a system where a typical fight takes up most of a session so that a player who chose to go with an unorthodox equipment combination will have a bad time for that whole time. You want combat to be about mowing down hordes of mooks with the occasional tougher enemy that takes a few hits to take down, and some very rare fights against boss type monsters that shake things up. You want a typical fight to be against 20+ enemies rather than a more typical 3-10, but most of those enemies should die on a single hit.
I think you also want the characters to have enough abilities that interact with the item abilities to make some items clearly better for some characters, or at least clearly different. For example, if one character has an ability that makes lightning attacks chain to additional enemies and another character has an ability that increases the range of lightning attacks, who has more use for the short-range lightning bolt thrower? Is it more useful to kill more enemies close-up or to be able to pick off more dangerous ones at range?
Another thing to take into consideration is that even with a fairly simple combat system, a TTRPG will never be able to match the pace of a computer game. On the other hand, with a TTRPG you will (hopefully) not be playing through the same story over and over and over again until it becomes more of a nuisance because it stops you from getting straight to the fight-loot-equip loop so there’s a much greater potential for the consequences of the fight to be interesting.
It was also noted upthread that there are boardgames that do this style of game quite well, like Descent, Zombicide, and Shadows of Brimstone. Rather than that being an argument against making this type of TTRPG, I think those are examples to learn from when making this type of TTRPG, especially when it comes to combat rules.
One inspiration that can be taken from them, which I think was also mentioned, is the use of cards. Used correctly, I think cards could be used to both make the items feel more substantial and simplify the loot division process. I think you probably want to use card combinations rather than have each item be a single card, if only to retain that sense of RNG created loot.
To sketch out my ideas for a combat system very stream-of-consciously (bullet-pointed after the fact because it turned into one long-ass rambling paragraph):
- I would start by using zones to simplify range calculations and terrain effects.
- There would be no numbers treadmill - player hit points will go up, but their offensive capabilities will be based around how many enemies they can take out and how powerful effects they can create rather than damage numbers.
- Similarly, enemies will be on a simple scale of something like minion (one hit point), grunt (two hit points), lieutenant (enough hp that it takes one character two turns to take them down, so maybe five?), and boss (enough hp that if the whole party goes all out on them it takes at least three turns to take them down).
- Character classes/playbooks should be clear archetypes with fairly free advancement to enable different builds for replayability, so ability pools rather than trees, with the power coming from synergies between abilities and between abilities and equipment.
- Equipment should be fairly limited, like armor, a couple of weapons, and one or two utility items. (The ability to have more equipment could also be part of increasing in power.)
- Items would be generated through card draws, with one card for the base item, up to maybe two or three for positive abilities, and sometimes a drawback.
- Most characters should be able to use most items, with effectiveness for a particular character being determined more by build and synergies rather than class.
- Players should make at most one die roll during their turn (though that could involve a couple of dice), and no rolls outside their turn.
- Enemies probably shouldn’t roll at all so player characters deploy defenses on their own turn.
- Most characters should probably have some kind of resource management system to keep their turns from being to samey and to add some more texture to the rules. This could be long-term (stretching over multiple combat) and/or short-term (from turn to turn).
- Enemies should generally be fairly predictable to avoid the players doing a lot of second-guessing and trying to figure out what possibilities they need to prepare for.
- A campaign should have a finite, fairly short, length. I think I would aim for three to five sessions, with two or three quick combats per session depending on how much else is going on, and an apetizer followed by a single epic boss battle for the last one. (Or perhaps two boss battles, so you can get some epic loot from the first to use in the second?)
Whew, that got a lot longer than I had thought. Time to go back to bed now.