Recently I started to think about running a campaign in low fantasy setting, where magic is limited both in number and scope of power. Some time passed and I still think about that idea, so (at least if I am not mistaken) it was not a temporary "oh, that's cool" moment, but an idea for a campaign I would not want to go to waste. The problem started when I wanted to pick an appropriate system for that from those I knew fairly well.
Considering the campaign theme: it was about a group of monster hunters going against what was considered by normal society "monstrous and impossible to beat", as well as having magic in limited form, as well as greatly reduced influence from eldritch beings or otherwordly phenomena.
On the problem
Many of the systems I played just don't cut it:
- Shadow of the Demon Lord is literally centered around an eldritch being and otherwordly phenomenon (demon lord and his shadow), which is quite visible in mechanics of the system. Not to mention magic in this system is unreal, some spells going on the plot-ending scale. Sooo, no.
- Cthulhu 7e is similar. Also, it is made around the "detective" part of the mythos and unraveling clues, not fighting. Which in a fight heavy campaign is the opposite of what you want. I do not want my players to make new characters every third session, or deal with mentally broken ones every second one.
- Fragnarok is a system for one-shots, not campaigns.
- Neuroshima 1.5 is a system built into the specific, futuristic world, and the world is a part of neuroshima 1.5 ruleset, which in an entirely homebrewed world is a problem. And there are many problems with the system I personally do not like, so no.
Which left me without really other choices but to go to my first, and most familiar system - D&D 5e. But before, you know, an actual question I came here with, the helping question: is there a system, that could work for this idea? I believe Warhammer whatever edition won't cut it - I know nothing of those systems, I never played one, and they seem complicated enough to not wanting to pick them up and work them into what I think I want. I have heard about Witcher RPG, but cannot say if it would be good for such an idea. If you know a relatively quick to learn system, that would fit right in, I would be glad for you pointing me in the right direction. If not, just skip this whole part, and thanks for reading anyway.
The actual problem
Theoretically, the best I would feel when running in D&D 5e. But the problems were quite obvious. Dungeons and Dragons is in no way or form low-fantasy from the mechanical perspective. Some high level spells or abilities are beyond whatever can be sanely called "low fantasy". The world can be made to reflect what I want of it, the problem is with players and their options. But knowing how popular this system is, I knew for a fact someone somewhere had similar problem. So I started digging.
Skimming through the internet I came across something called E6, a variant rule for Pathfinder 1e and D&D 3.5e. I know 5e very well, and I am aware those systems are closely tied, so I thought about running the campaign in 5e D&D with E6. But as much as I know 5e, I do not know much about 3.5, nor Pathfinder 1e or 2e. So my question is: What problems would appear in applying this rule to the 5e system, if any? Would there be problems with the way feats are being treated in 5e in contrast to 3.5e? Maybe something with progression after that 6th level? I can see some, but I'm most afraid I just miss on something big, and problems will start piling up after the start of the campaign, making it a nightmare midway.