How many copies did Alien Swarm sell?

1.1M to 1.8M copies, based on its 22k Steam reviews. This is a labeled estimate from the review count, not exact sales.

How much revenue did Alien Swarm make?

Alien Swarm is free to play, so there is no copy-sales revenue to estimate.

How big is Alien Swarm?

Estimated owners: ≈ 1.1M–1.8M; from 22k reviews (Very Positive)

A labeled estimate from the public review count (adjusted for release year), not exact sales. Owner data cross-checked with SteamSpy.

Does this actually work?

We left Alien Swarm out and predicted the genre from its 8 similar games. Every figure here, including Alien Swarm's, is estimated from Steam reviews, not self-reported sales.

Copies, estimated from reviews

typical (middle half) 32.2M–41.2M

best case 123.4M (PUBG: BATTLEGROUNDS)

The Survival genre

All 8 of your similar games are hits. A big, proven genre for a game like yours.

A hit here: 1,000+ reviews, roughly $150k+ before Steam's cut (a standard indie benchmark).

A typical game

≈ 32.2M–41.2M copies

≈ $93.2M–$165.8M after Steam's cut

from ~739k reviews

Best case

≈ 94.0M–152.8M copies

PUBG: BATTLEGROUNDS

A breakout hit, far above a typical game.

The genre you'd be entering

Your set: Your set clusters on Survival (4 of 8) and FPS (3 of 8).
The winners: Winners here lead with Survival + Shooter, priced around $10. The breakout hits carry Battle Royale + PvP + Third-Person Shooter; a typical game here doesn't.
The era: The games you compared span 2007 to 2020, a genre with a long track record.

Copies and revenue are rough lifetime estimates from the review count.

Similar games

Game	Est. copies	Est. revenue	Price	Reviews	Tags
Unturned 2017	Est. copies ≈ 19.4M–31.5M SteamSpy 50M–100M	Est. revenue Free	Free	564k reviews Very Positive	Free to PlaySurvival
PUBG: BATTLEGROUNDS 2017	Est. copies ≈ 94.0M–152.8M 3.7x vs typical SteamSpy 100M–200M	Est. revenue Free	Free	2.7M reviews Mixed	SurvivalShooter
Rocket League® 2015	Est. copies ≈ 26.9M–43.7M SteamSpy 10M–20M	Est. revenue Free	Free	580k reviews Very Positive	MultiplayerFootball (Soccer)
Apex Legends™ 2020	Est. copies ≈ 27.9M–45.4M SteamSpy 100M–200M	Est. revenue Free	Free	1.1M reviews Mixed	Free to PlayBattle Royale
ARK: Survival Evolved 2017	Est. copies ≈ 26.6M–43.2M SteamSpy 20M–50M	Est. revenue $109.6M–$294.7M after Steam's cut $199.3M–$453.4M before the cut	$14.99	773k reviews Very Positive	Open World Survival CraftSurvival
Warframe 2013	Est. copies ≈ 34.9M–56.7M SteamSpy 20M–50M	Est. revenue Free	Free	671k reviews Very Positive	Free to PlayAction RPG
Among Us 2018	Est. copies ≈ 22.5M–36.5M SteamSpy 20M–50M	Est. revenue $30.8M–$82.9M after Steam's cut $56.1M–$127.5M before the cut	$4.99	739k reviews Very Positive	MultiplayerSocial Deduction
Team Fortress 2 2007	Est. copies ≈ 64.6M–105.0M 1.7x vs typical SteamSpy 50M–100M	Est. revenue Free	Free	1.2M reviews Very Positive	Free to PlayHero Shooter