(suggestions at the end) It's pretty good. There are a few problems I have - mainly that the punctuation is a little unusual (though it is getting better) and that the system is a little different to the one in The Gamer - not too bad, but it feels a bit all over the place, but I do like the (minor spoiler for chapter 9) whole quests made from the subconscious, and some of the skills, but I'm not much a fan of how it doesn't seem faithful to the original in some aspects - like Gamer's Body doesn't seem to work as well, with how getting a sword in the arm caused him to get a bleeding debuff that drained HP crazy fast that wouldn't have happened in The Gamer, or how at the 50 milestones for a stat, he isn't getting any perks. Plus, some skills seem to be levelling way too fast - like getting level 20 to 28 in 3 different swordsmanship skills he didn't have before the fight in chapter 8 that wouldn't have levelled simultaneously, it just seems a little too fast to me.
I get this might not be made to be a 1-1 copy of the Gamer System in The Gamer, but it seemed like the author was going for that, and yet the MC seems to be underutilising it in some parts, then out of nowhere, growing 10X faster when he needs it. Considering there's no Abyss Auction in this world, and no Mages or magicians, and not even other IDs like ones with 10X the flow of time inside at the start (even if the MC might eventually get one of his own, it'd take time), there isn't the Great Labyrinth Era to level up from, there isn't any magical items to multiply your overall attack and defence power through magic 5X or to regen mana twice as fast, unless he gets a skill for it - he won't be making armies of Golems or giant great pillars to weaken the enemy and strengthen allies, plus people in this world seem to be much more tricky to fight with so many people that can level cities, if not - entire islands, having stuff like a conceptual ability to eat anything, to create shockwaves with a punch, to become a Phoenix with a crazy regen power, to throw around waves of hyper powerful venom, or to even become light - I feel that unless he keeps getting crazy skills like the most recent one man army one, that he could probably do with something more like stat based perks - even if it's only every 100 points.
Or possibly, the MC could get something for Devil Fruits - like maybe being a Gamer, he could - like skill books - absorb a devil fruit to get the power with no curse and no limit to the number of them, or maybe he could eat unlimited, but the sea curse will get worse until even just drinking water or rain paralyses him, which could be mitigated by maybe a skill related to either Devil Fruit resistance, Devil Fruit Curse Resistance, Or just Curse Resistance - the first giving a resistance to everything Devil Fruit, be it another's power, or your own's curse. The second working on just reducing the effects your one's curse does - which could be levelled by prolonged exposure to the sea or seastone or trying to move/train in it - so at level 50 for 50%, he could a second fruit and only have the normal levels of weakness, or at 80% resistance for level 80, with only two, he'd have 40% of the curse's effects - allowing him to stay conscious and slightly move - maybe like at a walking pace - in the sea, or when exposed to seastone, but not swim or use Devil fruit powers - having to max it out to 100 for 100%, or maybe having a skill evolution to Super Resistance which would go from 99 at 99% resistance, then evolve to super resistance with Level 1 giving 99.01% resistance - going to 99.02, so on and so forth until level 100 to unlock immunity (just to not be too OP, so the MC can't quickly max it out, then find and eat like 20 fruits and train them all during the timeskip to become an unbeatable god with 20 awakened fruits).
Sorry if I seem like I'm complaining a lot, I tend to be a little too critical in those things.
As a suggesting, I think it'd be cool if he could maybe - similar to Jihan in The Gamer (spoiler for a part of Jihan's system around chapter 150-220, I can't remember when) - make a base out of, instead of the house in an ID, the ship they go on has defences built akin to what Jihan prepared. Maybe something that weakens enemies within a certain distance of the ship, strengthens allies when near the ship, slightly boosts their growth in strength when near the ship, boosts the regeneration of HP and Stamina when near it, and maybe can notify them automatically when someone approaches or boards the ship to prevent enemies sneaking on it.
He could also prepare something to work as a forcefield that can be charged with mana, holding a capacity a couple times greater than his full capacity, which could be deployed to protect only the ship, create a forcefield slightly surrounding the ship and those onboard to prevent anything getting close (attacks, people / ships, or Sea Kings), or to work like a Bubbly Coral to allow travel undersea.
Maybe he could also make something like Magical Lasers built in to replace Cannons that he can charge with Mana, plus can be infused with Armament Haki to attack enemies, which can be manned by the crew, or maybe even the MC could - like in Tower Defence mode I hinted at earlier around CH 150-220 of The Gamer (even though I don't think they specifically did this), he could - make them automatic to shoot at enemies without need for anyone to control them, or maybe he could also go Jihan's route and make Golems which he could place on the enemy's ship to attack them or damage their ship while at sea. Might be overused in Gamer-System fanfics, but it was definitely both effective and cool.
Perhaps the MC could either upgrade the ship - be it by magical strengthening, or magically fusing better materials into the Going Merry to prevent needing a new one, or get a skill or maybe a system function based upon building himself a base / ship to then enhance it with mana or tech, or even make a field in which no one that isn't registered by the MC can use their Devil Fruit - acting like seastone / the sea, or just blocking the ability, and maybe even make the ship larger, or instead he makes the new ship instead of getting the Thousand Sunny, or perhaps the MC could help in the Thousand Sunny's creation to make it a LOT bigger - like comparable to the Moby Di (censored in fear of shadowban) Whitebeard uses in size, to allow for more space to store Golems if you do go that route.
Another thing I thought of is - similar to how Gild Tesoro in The One Piece Film: Gold (if I'm not mistaken) flooded his Gran Tesoro ship-city with gold - from his devil fruit, the MC could create a barrier to contain mana - which he could fill with any excess mana he has limitlessly, with the barrier containing the mana inside and being linked to the ship - be it because it's a device on there that generates said barrier, or because the spell is bound to it. He could, at any time, utilise this magic to do whatever he wants - be it to be used to supply spells with insane amounts of magic, to be utilised as a means to - similar to Jihan with Mana Ropes - instantly tie up anyone with magic so strong from the large amount used that even the strongest of people would struggle to escape, or to be used akin to a form of telekinesis - with all the mana coming from the MC, maybe he could better manipulate it so that he can leave it and use it later to move anything as if by telekinesis that the magic touches Via a mana control skill, or even to be used so that it can be absorbed to refill his own mana or to be condensed by shrinking the barrier to a palm-sized orb with many times more MP than the MC's full capacity that'd be used like a handheld nuke of mana - akin to his own, hand-crafted version of the Ancient weapon Pluton's island-destroying attack (if he charges it enough. Maybe he can prepare it as a gift for the 5 Elders of the WG, or even as a snack for Kaido or Big Mom?)
One last thing I can think of is if he could get a skill - either through creating or tinkering with tech to get a craftsman one, then practicing imbuing magic to get an enchanting skill (or through a quest reward) which he then uses together, or as a fused skill to make magical equipment and accessories to boost his and maybe also the crew's power - like enchanting Zoro's swords (though he'd probably refuse) or clothes, or even his earrings to allow him to heal faster, get a strength or dexterity boost, be able to sense where his allies are (to not get lost so often, even though it might not be of much help), to recover stamina faster, or to (when he gets it) improve his Haki's strength. Same applies to everyone else, maybe also with clothes that are self-cleaning and repairing, plus maybe an enchantment on weapons like Sanji's boots to generate flames or more flames when he gets the ability, increase Zoro's swords' sharpness and maybe utilize flames, electricity, or something if he would allow, enchant Luffy and other devil fruit user's equipment to give a small resistance to the sea curse or to cause them to automatically float in the sea, and maybe an extra boost to Luffy's overall stamina and stamina regen for when he unlocks Gear 5 to deal with the strain of it.
Sorry for talking so much, but I hope this gives a couple of ideas, even if none of them are used.
