The Steam Workshop's Install Monopolies (2026): In 32 Games One Mod Owns More Than a Tenth of Every Install — and in One, Two Mods Hold Half the Ecosystem

Every "most subscribed" list on the Steam Workshop answers the same question — which mod is biggest — and every one of them stops there. The more useful question is the one underneath it: when a game's players install something, how few mods does it take to account for half of them? That number is the ecosystem's real structure, and nobody publishes it.

We measured it for every Workshop game with enough of a catalogue to be meaningful. Across 5,993,986 active, subscribed mods in 348 games carrying 12.49 billion lifetime subscriptions, the answer is that installs pool the same way in almost every ecosystem, and the pooling is more extreme than the leaderboards let on.

Platform-wide, the top 27,975 mods — 0.47% of the entire catalogue — account for half of every subscription on Steam. Widen to the top 454,739 — 7.59% — and you have covered 90% of the platform. The other 92% of the Workshop, six million mods, split the remaining tenth.

That is the platform. The interesting part is what happens when you stop pooling and look at each game on its own, because the shape repeats at every scale — and then, at the extreme ends, it flips.

The install-monopoly ranking

Take each game's installs, sort its mods from most-subscribed down, and find the point where the running total crosses half. That gives the number of mods it takes to "own" the ecosystem. As a share of the game's own catalogue, here is the ranking:

Read the middle column against the right one. In Unturned, a 74,000-mod ecosystem, 36 mods hold half of everything installed — and its top ten alone hold 36.9%. In Tropico 6, six mods out of 4,396 (0.14% of the catalogue) account for more than half its installs, and its top ten hold 58.5%. The single biggest mod in Tropico 6, Paradise Island, is 18.6% of every subscription the game has.

For contrast, Wallpaper Engine — the largest Workshop on Steam, 119,397 mods and 1.98 billion subscriptions — needs 4,301 mods to reach the same halfway point, 3.6% of its catalogue, and its top ten hold just 1.9%. The same metric, the same platform, a 72-fold difference in how concentrated the installs are.

Where a single mod is an ecosystem

The sharper version of the same question: in how many games does one mod hold at least a tenth of every install? The answer is 32 of the 348. These are not the games with the most mods — they are the games where one download became the whole reason people opened the Workshop.

The mechanism differs by game and the numbers make it legible. In They Are Billions, The 50 Days Challenge at 1.87 million installs is a single canonical survival challenge that the whole community runs; the next-biggest mod is 97,953 — a 19x cliff. In Survive the Nights, Balanced Survival (Hard) at 194,989 installs is more than seven times the second-place mod. These are ecosystems where the Workshop's own discovery stopped mattering, because the answer to "what should I install first" is the same answer for everyone.

The pattern is not "small games are concentrated" — that would be trivial. Counter-Strike 2 is here with 30,102 mods and a 39.7-million-install crosshair generator, and a crosshair generator is exactly the kind of utility where everybody installs the same one. The concentration follows substitutability: the easier it is for one download to make every other one redundant, the closer the game gets to a single-mod monopoly.

The inversion: the tightest ecosystems are the most reachable ones

Here is where the ranking stops being a curiosity about giants and becomes something a creator can use. If you line all 348 ecosystems up by that "share of catalogue needed for half," and cut them into quartiles, the tightest quartile and the deepest quartile tell opposite stories:

The correlation between how monopolised a game is and how likely an ordinary mod is to reach 1,000 subscribers runs +0.42 — and it is positive, which is the counter-intuitive part: the games where a few mods own the installs are the games where the median mod struggles most to find any audience at all. In the 18 ecosystems where the top ten hold half or more of the installs, the median mod reaches a thousand subscribers 3.6% of the time. In the 121 deep-shelf ecosystems, where the top ten hold under 12%, the median mod reaches it 16.0% of the time — 4.4x more often.

The giants are not the monopolies. A monopolised ecosystem — Tropico 6, Survive the Nights, Becastled — is one where the community has picked its winners and stopped looking. A deep shelf — Wallpaper Engine, Garry's Mod, Cities: Skylines — is a real market where a new mod competes on its merits. That is the same distinction this series keeps finding at the creator level: five creators hold 73% of Aimlabs' subscriptions while Wallpaper Engine's top five hold 5.7%, and it is the same shape whether you count creators or individual mods.

The deepest shelves

Trailmakers is the extreme: 332,829 mods, and it takes 12,124 of them to reach half of the game's installs. Its top ten hold 1.6% of installs between them. But 0.9% of Trailmakers mods ever reach a thousand subscribers — the deepest shelf is not the same as the safest bet, because a shelf that deep is where the game itself is a sandbox that mints disposable creations. Wallpaper Engine is the opposite balance: a deep shelf and the highest reach of any large ecosystem, because its discovery surface treats every wallpaper as a candidate for the front page.

The small-game outlier is worth naming: Automation: The Car Company Tycoon, 737 mods, 206 for half (27.95%) — and 99.2% of its mods reach a thousand subscribers. It is a game small enough that the Workshop is the content, and almost everything published in it lands. It is the cleanest counter-example to "concentration means opportunity."

What this is not

Two honesty notes, because this series has been burned before by a number that looked like a story.

Half of a small game is not half of a market. "36 mods hold half of Unturned" and "4,301 mods hold half of Wallpaper Engine" are the same shape measured on two different-sized denominators. Neither number is a statement about absolute installs — Unturned's 90 million subscriptions are 4.5% of Wallpaper Engine's 1.98 billion. The share tells you how the game's own players behave; it says nothing about how many players there are.

Concentration is a snapshot of a stock, not a flow. Subscriptions only accumulate, never decrement while a mod lives, so an old mod with a head start keeps its lead mechanically. That is why this is the stock counterpart to the momentum economy, where the weekly new subscriptions are even more concentrated — under 1,000 mods took 83% of one week's new installs. The monopolies here were earned over years; the concentration of new demand is sharper still.

The Workshop is a market where installs are the only real currency, and when you actually count them, 92% of the catalogue is competing for the last tenth of the platform. The games where that is worst are the ones where a single download already answered everyone's question — and the games where it is least bad are the ones where the shelf is deep enough that a new mod can still find a stranger.

Method: ModSignal's live dataset of active Steam Workshop items, filtered to is_active items with at least one current subscription, across the 348 games with 200 or more such mods. "Mods for 50%" is the count of top-ranked mods whose cumulative subscriptions first cross half of the game's total; ties are rare and do not change the crossing point. Data as of October 2, 2026.