Ordered by installs · Not tested by us
The 20 most-installed Universe Sandbox mods (2026)
Ordered by Steam Workshop subscriptions, which is a count from Valve rather than a judgement from us. We have not installed these, and say so rather than implying a verdict we have not earned. Everything here installs by clicking Subscribe.
The short version
- Most installed: Nuclear War Simulation, 52,673 subscribers.
- 0 of 20 updated since the start of 2025, which matters more than subscriber count for whether a mod still works.
- All install through Steam. Subscribe on Workshop and the game picks it up on next launch. Nothing to unzip.
All 20, most installed first
SimulationsUpdated 21 June 2018
SimulationsUpdated 22 May 2021
SimulationsUpdated 19 November 2018
SimulationsUpdated 22 March 2021
SimulationsUpdated 21 November 2018
SimulationsUpdated 22 November 2018
SimulationsUpdated 28 September 2020
SimulationsUpdated 23 June 2018
SimulationsUpdated 18 November 2018
SimulationsUpdated 27 June 2021
SimulationsUpdated 3 April 2023
SimulationsUpdated 18 November 2018
SimulationsUpdated 15 January 2019
SimulationsUpdated 25 June 2021
SimulationsUpdated 3 October 2021
SimulationsUpdated 4 December 2018
SimulationsUpdated 2 July 2018
SimulationsUpdated 2 July 2018
SimulationsUpdated 20 June 2018
SimulationsUpdated 15 June 2018
Subscriber counts and approval scores are Valve's, read on 5 September 2026 and not adjusted by us. Browse the full Workshop.
Common questions
What is the best Universe Sandbox mod?
By installs, Nuclear War Simulation, with 52,673 Steam Workshop subscribers. That is the most-installed rather than the best: subscriber count measures how many people tried it, not whether they kept it. Workshop's own approval score is shown next to each one where Valve publishes it.
How do I install Universe Sandbox mods?
Everything on this page is a Steam Workshop item, so installing means clicking Subscribe on its Workshop page and letting Steam download it the next time you launch the game. There is nothing to unzip and no files to move. Unsubscribing removes it. Mods from outside Workshop work differently and are not covered here.
Are these Universe Sandbox mods safe?
They are hosted by Valve and distributed through Steam, which is a meaningfully lower risk than downloading files from elsewhere, but Valve does not audit mod code. We have not run any of them. Treat a mod with a large subscriber count and a recent update as better evidence than one with neither.
How is this list ordered?
By Steam Workshop subscriptions, highest first, read on 5 September 2026. That is a count from Valve, not a judgement from us. We have not ranked these by quality and do not have the basis to: nobody here has installed all 20.
Do you get paid for these?
No. Mod authors are not paid by us and cannot pay for a position here. The order is Valve’s subscriber count and nothing else.