RKSI Incheon International: sold at 95 per cent, and the community is finishing the rest

Buried in the change list for version 0.9.8, between "Air supply units added" and "Blue light stick clean up", there is a line that thanks a person called Bald Eagle, of the Fly Together Korea Community, for the AFCAD coding. AFCAD is the invisible layer that tells the simulator where the stands are, which taxiways connect to what, and where an aircraft is allowed to hold. It is the least glamorous file in an airport add-on and the one that breaks the most flights. On a €22.99 payware rendition of the busiest airport in Korea, built by a Thai developer, that file was written by a Korean volunteer.

That is not a scandal. It is the product. SiamFlight is one person — he says so himself, on the official forum, in the same post where he admits he badly misjudged the job: he underestimated the size and detail of Incheon, having built Bangkok Suvarnabhumi and assumed Seoul would be no harder. Eight or nine months of work later he put RKSI on sale as an Early Access build, version 0.9.5, on 26 March 2026, at what he described as roughly 95 per cent complete. Five months on, at version 0.9.8, it is still Early Access, and the remaining five per cent is being closed partly by him and partly by strangers.

The marketing calls it "a community-driven passion project created in close partnership with the dedicated South Korean flight simulation community". In most store copy that sentence is decoration. Here it is a description of how the thing actually works. The AFCAD came from Korea. The GSX Pro profile — which SiamFlight's own listing still promises as a future update — came from a volunteer on flightsim.to the day after launch and has passed eight thousand downloads. The static aircraft, which the scenery does not include, came from somebody else again. Take the volunteers away and you have an empty, beautifully lit, extremely large airport.

We read every public source we could find on this add-on, and the striking thing is how thin the record is for a product covering one of the ten busiest airports on earth: three store reviews on simMarket, one on flightsim.to, nine ratings in the in-sim Marketplace, two small YouTube flyovers and not a single written review or forum argument anywhere. Reddit, which would normally be the sentiment check, is unavailable in our research environment and has been for every review in this series, so treat its absence as expected rather than as evidence. What follows is drawn from twenty sources.

What you are actually buying

One product, one 1.53 GB download, one price, five storefronts. There is no separate MSFS 2024 SKU, no upgrade fee, and no second build to install. Every store sells the same file and every store lists both simulators.

Store	Price on 20 August 2026	Version on the page	Notes
simMarket	€22.99	0.9.8	Delivered through simMarket's app only. PID 21030, listed 28 March 2026
flightsim.to	$26.99	0.9.8	The developer's own announced launch price
iniBuilds	£20.29 + £4.06 VAT	0.9.8	£24.35 delivered
Orbx Direct	US$27.69 / €23.71 / £20.33	described as 0.9.7	Requires Orbx Central; page reports 1.52 GB where the others say 1.53 GB
In-sim Marketplace	USD 26.99	last updated 25 June 2026	Listed since 2 April 2026

Nobody is meaningfully cheaper. simMarket's terms say displayed prices include whatever value added tax applies, which for an unresolved browsing session means none — so €22.99 is a pre-tax figure and an EU buyer will pay more at checkout. iniBuilds shows the tax on a separate line. Orbx says VAT is included where applicable. Strip the tax treatment out and the four PC stores land within about a euro of each other, which is what you would expect when the developer set a single dollar price and let the shops convert it.

What matters more than the euro is that this is the most expensive thing SiamFlight has ever sold. Their simMarket shelf carries nineteen products and the next dearest is Phuket at €17.49; most of the catalogue sits between €6 and €14. RKSI is also their first airport outside South East Asia. It is a departure in scale, in geography and in price, and it went on sale unfinished.

What is in the box

Terminal 1, Terminal 2 including the Phase 4 expansion that opened on 3 December 2024, and the satellite Concourse are all modelled, along with cargo aprons 1 and 2, the cargo maintenance apron, the perimeter, the southern solar farm, a coast guard helicopter station and the Paradise City and INSPIRE developments on the horizon. Parking is numbered to the AIRAC. Navaids, ILS, LOC, VOR/DME and RVR are in. Night lighting is in and is the best thing about the screenshots.

What is not

Static aircraft. Static people. The developer's own GSX Pro profile. Custom VDGS. Living-world service vehicles. A finished Terminal 1 interior — the developer said on 17 April 2026 that the T1 exterior model itself was wrong and needed rebuilding before the interior could go in, and that when it arrives it will not be an interior simulation. Full ground clutter, which only started appearing around T1 and the Concourse in the 0.9.8 build of 21 June 2026. All of these are on the published future-updates list, which is honest, and none of them has a date, which is not the same thing.

What the community consistently praises

It runs

This is the finding that repeats everywhere, and it is the one that matters at an airport this size. The German-language reviewer on simMarket, writing on 29 March 2026, rated performance in MSFS 2024 as excellent and called it the best-performing of the RKSI sceneries then available. The Traditional Chinese reviewer, the day before, made the same point from the other direction: the interiors are not stuffed with clutter, so there is no stutter disaster. simFlight's release notice of 31 March 2026 read the same restraint into the design.

It is not an accident. Look at what the two post-launch updates actually did. Version 0.9.7, on 17 April 2026, removed an RPN script and began splitting models and adding LODs. Version 0.9.8, on 21 June 2026, was explicitly an optimisation and texture pass: LODs on Terminal 1, further optimisation of jetways, boarding gates and aerobridges, models sliced into smaller pieces. In between, on 18 May and 5 June, the developer posted work-in-progress notes saying in plain terms that he was not adding anything, he was making it lighter. Whatever else is unfinished, the frame-rate work has been done first and done deliberately.

The layout is current

Every competing RKSI for MSFS predates the Phase 4 expansion. PacSim's, released 24 September 2022, is the well-regarded one and is four years old; the Le Aero Design version on simMarket dates from 19 March 2023, sits at v0.9.1, and its own store reviews note that the developer's site went dark in early 2024. A forum poster put it bluntly on 30 April 2026: PacSim's Incheon is out of date and missing a terminal. SiamFlight's is the only paid rendition that shows Incheon as it is now, with the expanded Terminal 2 and the fourth runway in use.

Somebody is checking the details

The 0.9.7 change list is a page of corrections that only a person who knows the airport would raise: gate 224 renumbered to 223, gate 102's missing stand, gate 128 missing entirely, gate 352's parking spot flipped, the cargo taxiways renamed to D7/D8 and D9/D10, an Asiana cargo logo replaced with the correct operator, stands realigned to their spots. That is what feedback from local simmers looks like when a developer acts on it, and it arrived three weeks after launch.

Night lighting

Every promotional shot the developer has released since June is a dusk shot, which tells you where he thinks the product is strongest, and the record does not contradict him. The 0.9.8 build added missing stop-bar lights, cleaned up stray light sticks, and put ALSF-2 sequenced approach flashers on the runways for MSFS 2024 specifically. Improving the building illumination maps is still on the to-do list.

What keeps coming up as a problem

Textures — still open

The single substantive criticism in the entire public record comes from aniiran, the only reviewer on flightsim.to, on 30 March 2026, scoring it 3 out of 5. He owns SiamFlight's Suvarnabhumi, expected the same standard, and did not get it: he named "low quality textures especially for the ground tiles", roofs and interiors, said the modelling is good rather than amazing, and called the layout accurate and up to date. He also said he expected it to improve. Version 0.9.8 was a texture pass, so it has been worked on; nobody has published a verdict on whether it worked.

The airport is empty — still open

The scenery ships with no static aircraft, and a forum regular noted on 27 March 2026 that SiamFlight "isn't known for putting any static people in interiors" either, unlike PacSim, Aerosoft or iniBuilds. So the terminal you can walk into is a bright, well-modelled, completely deserted check-in hall, and the aprons are bare unless you run AI traffic or install a third-party pack. Somebody did make that pack — an AIG-based static set appeared on flightsim.to in mid-2026 — but it is MSFS 2024 only, and the two comments under it are both people asking for a 2020 version.

It is still 0.9.8 — still open

Three released builds in five months, and the last of them was 21 June 2026. As of 20 August there has been no 0.9.9, no 1.0, and no published date for one. The developer's stated intention is to keep updating long after release, and his track record on nineteen other airports supports that; but a buyer today is buying a product its author has not yet called finished, at a price higher than any finished product he has ever sold.

The developer's own GSX profile still does not exist — still open

The German simMarket reviewer flagged GSX jetway problems on day two and forgave them as an Early Access artefact. What actually solved it was a volunteer: a GSX Pro profile by LunaLottie went up on flightsim.to on 27 March 2026, the day after launch, has been maintained to v2.5.4 as of 28 June 2026, and has cleared eight thousand downloads against a 4.8 average. SiamFlight's own listing still carries "GSX pro profile for PC version" under future updates. That is a promise a stranger kept first.

Nobody is talking about it — and that is itself the problem

There is no AVSIM thread on this scenery. There is no written review on FSElite, Threshold, MSFS Addons or anywhere else — only release notices that reproduce the press copy, one of which, simFlight's, still described MSFS 2024 as an upcoming platform in March 2026. The two YouTube videos are flyovers from channels with 467 subscribers and fewer than 1,400 views between them. Support runs through a Discord with 237 members that a forum user reported on 14 July 2026 he could only find buried in a Facebook post, plus a Hotmail address. For a hub airport with a large, active Korean simming community, the visible English-language record is close to nothing.

The store listings are out of step — still open

Every storefront sells version 0.9.8 under body copy that still says v0.9.5, and Orbx Direct's page describes v0.9.7 and reports a smaller download than the other three. simMarket's requirements block does not name a simulator version at all; it just says "Microsoft Flight Simulator". If you are trying to work out from the shop what you are buying, the shop cannot tell you.

Performance and stability

Nobody in the record reports a crash, a CTD, a black-square texture or a broken install. The complaints are about what is missing and how it looks, never about whether it works — which for a 1.53 GB scenery of a four-runway megahub released in an unfinished state is a genuinely good result.

On frame rate, the evidence is consistent and unusually specific. The developer runs his own tests on a 7950X3D with 64 GB and an RTX 4090 with FSLTL traffic loaded, and published the before-and-after of the Terminal 1 optimisation on 5 June 2026. Two independent store reviewers, in two languages, single out performance as the reason to buy. The design philosophy — open aprons, restrained interior density, aggressive LODs — is doing the work, and it is the direct answer to the one criticism that dogged SiamFlight's Suvarnabhumi, where owners on high-end hardware reported frame rates that needed frame generation to stay comfortable.

The 2020 versus 2024 question deserves an honest answer, because the store badges do not give one. This is one build that installs into both simulators and is sold once. It is architecturally a 2020-era scenery: Orbx's own taxonomy files it as a Microsoft Flight Simulator product marked "MSFS 2024 Compatible", and SceneryAddons records it as 2020-native and 2024-compatible. But it is not a lazy port either — the 0.9.8 change list contains at least one 2024-only feature, the ALSF-2 sequenced approach lighting, and the developer's own outstanding work list distinguishes between the PC build and the Marketplace/Xbox build. Practically: buy it on 2020 and you get everything except the 2024-specific lighting; buy it on 2024 and you get a 2020-generation airport that has been tuned for the newer sim rather than rebuilt for it.

Who should buy it

You fly Korea regularly and you are on MSFS 2024. Buy it. It is the only paid RKSI that matches the airport you would see today, it is the fastest of them, and at €22.99 it costs less than PacSim's ageing $28.99 rendition. Install LunaLottie's GSX profile at the same time.

You are on MSFS 2020 only. Buy it too, with one small deduction: the sequenced approach flashers added in June are 2024-only, and the rest of the package is identical. There is no version penalty and no second purchase later.

You already own PacSim's RKSI and it has been fine. Wait, unless the missing Terminal 2 expansion bothers you. PacSim is a top-tier developer with a v2 in the pipeline behind KABQ, and if you can live with a 2022 layout for another year you may end up with a better airport for the money.

You care most about a populated, lived-in airport. Do not buy this. No statics, no people, ground clutter only just beginning, service vehicles still on the wish list. You will be flying into an immaculate ghost town, and the third-party pack that fixes it is MSFS 2024 only.

You never buy unfinished software. Do not buy this either, and there is no argument to be made against you. It is version 0.9.8, it has been Early Access for five months, and 1.0 has no date.

Where it stands today

On 20 August 2026 this is the best Incheon you can buy for Microsoft Flight Simulator, and it is not close, because the competition is a four-year-old scenery awaiting a rewrite and a three-year-old one whose developer appears to have gone quiet. That is a real advantage and it is also a fragile one: PacSim's v2 is announced, and the moment it lands SiamFlight's head start becomes a straight quality comparison he has not yet won on textures or on ground life.

What he has won on is speed, currency and follow-through. Three builds in five months, each one documented line by line in public, each one visibly responding to something a customer said. The version number has moved 0.9.5 to 0.9.7 to 0.9.8 and stalled there since June, which is the longest quiet stretch since launch and the thing to watch. If 1.0 arrives with the Terminal 1 interior, the ground clutter and the developer's own GSX profile, this becomes a straightforward recommendation at any price he cares to charge. If it does not, a lot of people will have paid a premium for 95 per cent of an airport.

The most interesting thing about it, though, is not the score. It is that a Thai developer, working alone, built Korea's national gateway by asking Koreans what was wrong with it, and then let them fix the parts he could not. The AFCAD credit in the 0.9.8 notes is the whole business model in one line.