Radical Heights, a weaponized version of the game show Supermarket Sweep, has had a successful launch into the Early Access portal for unfinished games on Steam this week. That’s great news for Lawbreakers studio Boss Key Productions, which made this battle royale shooter, and it’s bad news for the guy on Steam who promised to buy everyone a game if it found an audience. But how is this knockoff getting any attention in a genre that already has dominant cultural juggernauts like Fortnite and PlayerUnknown’s Battlegrounds? Simple: It found a niche by going free on Steam.

This is going to sound familiar: Radical Heights is a shooter where 100 players drop onto a map to fight each other until only one person is left standing. Like in PUBG, you can equip armor and helmets, and you can aim down sites. Like in Fortnite, you can find loot with color-coded rarity. It differentiates itself from those competitors with its 1980s game-show theme and a shopping system where you can buy weapons from vending machines using money that rolls over from match to match. But at its core, the gameplay doesn’t stray far from PUBG or Fortnite, and that’s one of the reasons that it works.

Here’s the lay the of battle-royale land at the moment. Radical Heights doesn’t cost anything to download and play. PUBG is $30. Fortnite is free, but it isn’t on Steam (you need the Epic Games Launcher). H1Z1 is free and also on Steam, but it is starting to feel more primitive than its competitors.

Radical Heights has come along and filled the gap on Steam for a free alternative to both PUBG and Fortnite that was informed by those games from the beginning (something H1Z1 cannot do). And it is already seeing the benefit of that with more than 12,000 people playing it at the same time on Steam yesterday during its peak hours. H1Z1 peaked at fewer than 9,000 players. Neither of those are anywhere close to PUBG’s 2.12 million peak concurrents from yesterday (Fortnite concurrents aren’t available), but Radical Heights doesn’t need to beat PUBG or Fortnite — it just needs to attract enough players for Boss Key to survive.

We’ve seen this strategy work before. In 2016, Blizzard Entertainment launched the class-based team shooter Overwatch, which was GamesBeat’s Game of the Year. Lawmakers, which debuted at $30 on Steam, failed despite having a lot in common with Overwatch, but another, even more similar game called Paladins from Hi-Rez Studios broke through and established its audience. Paladins was able to do that because it was free and available on Steam when Overwatch started at $40 and was only available through Battle.net. It likely also succeeded because it played a lot more like Overwatch and differentiated itself in some of its subsystems.

Radical Heights reminds me of Paladins, which peaked at 22,000 concurrent players yesterday, and I think that Boss Key’s games could settle into similar numbers. The studio will have to keep adding content and polish, but it has found a niche that it could potentially own.

What should have Boss Key buzzing (and cofounder Cliff Bleszinski is beaming on social media), is that Radical Heights is getting some positive feedback from high-profile players. Tyler “Ninja” Blevins, the biggest broadcaster on Amazon’s Twitch livestreaming video platform, ended up playing the game for hours last night for his tens of thousands of viewers. Ninja is best known for playing Fortnite, but — fortuitously for Boss Key — Epic’s servers crashed. So Ninja got into Radical Heights, and he gave it a strong endorsement.

Another popular streamer, Dr. Disrespect, who is best known for PUBG, also spoke highly of Boss Key’s rad game.

And with the help of the Fortnite servers and Ninja, Radical Heights spent a significant chunk of last night on top of the most-viewed games on Twitch. This isn’t going to last (or maybe it will — I was wrong about Fortnite), but again, that doesn’t matter as long as Boss Key has a viable, living game.