Does anyone have any novels where the MC has a system, but it doesn't make them stronger directly? Most novels with Systems have their MC gain EXP to raise their cultivation fast, have an exchange shop for famous abilities from other novels, rare bloodlines, and divine items. Honestly they just kinda blend together after a while, especially since they love stealing moves from Battle Through the Heavens (I've read 3 where the MC obtains the Angry Buddha Lotus Flame). I don't care what the system does, it could be like Scholar's Advanced Technological System where it just helps the MC learn about Science, or like Side Character Transmigrations, where the System transports the MC into other worlds against her will and she dies if she fails or is too evil. Anything is fair game as long as it's main function doesn't directly improve the MC's strength.
Well the system from When A Mage Revolts likely counts. It is more of a snarky partner to MC when they quarrel (it helps with analysis stuff and some tips but doesn’t do any direct strength boost) There is also The World After the Fall but that one basically has MC start with a system (he along with others have) until he is the only one left and he basically is able to leave the constraints of the system and makes it his mission to destroy the system that has made a crap world.
Experimental log of a crazy lich. It really does things with equivalent exchange: mc can accomplish it on his own -it will help, else it wont
Great Doctor Ling Ran, Mc has a medical system which helps him progress and gain techniques/experience in his medical path as a doctor (intern).
Well, there are these modern setting ones that aren't used for combat. Some examples: Chemistry God of Music Top Management I guess I Reincarnated Into a Vending Machine could fit your criteria. While the MC gets to be more versatile, it can only benefit the people around him.
I can think of one that is Utsuro no Hako to Zero no Maria. But I'm not sure if this is the type of novel you wanted...? It's got a system I believe. It's similar to Mirai Nikki in a way. There is a system involving the titular "box". The MC doesn't have any special power or anything other than being the natural opposing force of the box (or was it 0?). It's been a long time since I read it and it was also my first ever light novel so my memory is a bit fuzzy. Anyway, there definitely is a system in place and that's what the whole novel revolves around. The MC is directly connected to the system too, and that connection never gave him any noticeable power that he can use in battle or anything. In fact, I think the whole box exists to oppose him, not the other way around (which will explain why he doesn't have any power...cause the box or 0 was created based around an ordinary him). Edit: I just realized that first of all, this doesn't make any sense to someone who hasn't read the novel yet. And secondly, I just gave out a whole lotta spoilers. (But don't worry, you'll probably not even realize what the hell I'm talking about till the very end of the novel, or maybe even after finishing the novel...so could you really count that as spoilers?)
Population Control has a system that allows MC to sort of bend reality, but it's quite limited, and he can't make himself stronger or anything. He does make himself a bit younger but that's all he can do to himself. He has to be very inventive with the system to accomplish his mission. Also it's not a system in the game sense of the word.
Gourmet of Another World, maybe? The system would gave the MC some abilities to produce foods/cooking & drinks (ie: his restaurant could serve wines only after he reach a certain lv), but also giving him quest to make one. All while the one who got stronger (physically at least) due to MC leveling up is actually the robot bodyguard of his restaurant while he got more recipes, ingredients, foods & drinks
The closest I can think of is He Who Fights With Monsters. It's not what you're actually asking for, but it does have an unusual System. MC wakes up one day butt naked in a hedge maze with no idea what's going on. Then a System Screen pops up and tells him to figure out what's going on, probably by walking around, and it'll give him some pants as a reward. In short, this system does many of the normal System things, only adjusted for the world's eccentricities. So Yes to Drops, No to EXP. Yes to making things a bit easier for the MC, No to the MC gaining power-ups unique to him just because he has System. To showcase the world's differences to what we normally consider System Support, the MC only has 4 Stats, Strength, Speed, Spirit & Recovery. This corresponds to the 4 Attributes that everyone has that Essence can be Absorbed into, through which everyone in the world, including the MC, gains their Skills. After absorbing at least one Essence, that person gains a single Awakened Ability and the ability to absorb Awakening Stones to awaken 4 more Skills related to their current Essence. It is considered best practice to absorb all 4 Essence before Awakening Abilities, to give the best chance that the Awakened Abilities work together. While this is best practice, most do not have the ability to afford even one Essence, let alone the 4 required as a foundation, so it does not always happen. Everyone also has 6 Racial Abilities. 5 of the MC's is taken up by System and Typical System Benefits, like Inventory, Map, Quests, Automatic Language Translation Service (called something else, and includes other things) and the ability to see System, with the last being a Magical Affinity. We also get explanations for how the MC got to where he is, what's behind the System's wording choice and more. All in all, I think that you would enjoy this story's System, but it doesn't quite fit how I interpret your wording.
+1 Instead of an system that directly improves people's general 'strength', it's more of a system that enforces rules depending on the circumstance. I very much do recommend this novel even if it does not fit your criteria. It's one of my personal best completed novels....
I know I’m late and all, but Quickly wear the Face Of the Devil is a good one. Not sure if you’ve already read it tho
i am very late but i would say histories number 1 founder the system gives him the cultivation technique and things of that nature but he has too succeed himself because of the mission he get ps it mostly a sect building system he uses it less after a certain point as it becomes almost useless almost
Arrogant Young Master Template A Variation 4, I guess... The guy does get more powerful by using the system, but he has to do the cultivation stuff manually. One of the big things though is you have to sit still and concentrate for a long time to cultivate (obviously), but the guy finds it super boring. Unfortunately, the former owner of the body is known as a cultivation maniac and the MC is trying his best to not get caught by his family.