How many copies did Alien Swarm sell?

1.4M to 2.2M 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: ≈ 1.4M–2.2M; 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–46.6M

best case 124.1M (PUBG: BATTLEGROUNDS)

Games like Alien Swarm

The middle of these games

≈ 32.2M–46.6M copies

≈ $93.8M–$166.6M after Steam's cut

from ~745k reviews

Only the top fifth of 2019’s Steam releases earned about $34k gross, so plan for that or less.

All 8 of your similar games are hits.

No genre covers most of your similar games. The closest is Survival (4 of 8), so the genre you lead with is still undecided.

Of the 416 indie games that passed 1,000 reviews in 2022, 11.8% were novel genre mixes and 88.2% stuck to an established genre. Published indie market research.

Best case: PUBG: BATTLEGROUNDS at ≈ 94.5M–153.6M copies. 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. 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, and none of them shipped in the last two years.

How these numbers were worked out

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

Copies come from each game's reviews times a sales-per-review rate that falls with release age, from about 31 for the most recent game here to about 79 for the oldest, then widened into a range; revenue rides on that estimate times price. Source: GameDiscoverCo (2020) and VG Insights (2021).

Similar games

Game	Est. copies	Est. revenue	Price	Reviews	Tags
Unturned 2017	Est. copies ≈ 19.4M–31.6M SteamSpy 50M–100M	Est. revenue Free	Free	565k reviews Very Positive	Free to PlaySurvival
PUBG: BATTLEGROUNDS 2017	Est. copies ≈ 94.5M–153.6M 3.7x vs typical SteamSpy 100M–200M	Est. revenue Free	Free	2.7M reviews Mixed	SurvivalShooter
Rocket League® 2015	Est. copies ≈ 28.3M–46.0M SteamSpy 10M–20M	Est. revenue Free	Free	580k reviews Very Positive	MultiplayerFootball (Soccer)
Apex Legends™ 2020	Est. copies ≈ 26.4M–43.0M SteamSpy 100M–200M	Est. revenue Free	Free	1.1M reviews Mixed	Free to PlayBattle Royale
ARK: Survival Evolved 2017	Est. copies ≈ 26.7M–43.4M SteamSpy 20M–50M	Est. revenue $110.1M–$296.0M after Steam's cut $200.2M–$455.4M before the cut	$14.99	776k reviews Very Positive	Open World Survival CraftSurvival
Warframe 2013	Est. copies ≈ 42.7M–69.4M SteamSpy 20M–50M	Est. revenue Free	Free	676k reviews Very Positive	Free to PlayAction RPG
Among Us 2018	Est. copies ≈ 22.7M–36.8M SteamSpy 20M–50M	Est. revenue $31.1M–$83.6M after Steam's cut $56.5M–$128.6M before the cut	$4.99	745k reviews Very Positive	MultiplayerSocial Deduction
Team Fortress 2 2007	Est. copies ≈ 79.0M–128.3M 1.7x vs typical SteamSpy 50M–100M	Est. revenue Free	Free	1.2M reviews Very Positive	Free to PlayHero Shooter