Best Browser Games of 2016 (Slither.io Year)

2016 was the year the .io genre stopped being a one-game novelty and became a category. Slither.io launched in March and climbed to the top of the App Store’s download charts. Matheus Valadares released Diep.io in April. Mope.io showed up later in the year. Agar.io was still in its peak. The best browser games 2016 produced were almost all .io games — and that pattern shaped browser gaming for the rest of the decade.

1. Slither.io

Steve Howse released Slither.io on March 25, 2016. The iOS version reached number one on the App Store’s most-downloaded list, and by July the browser version ranked among the 1,000 most-visited websites tracked by Alexa. Snake-as-MMO turned out to be exactly the right idea at exactly the right time. The browser version stayed the canonical experience. For our full take, see our Slither.io review.

2. Diep.io

Matheus Valadares followed Agar.io with Diep.io on April 16, 2016. A top-down tank shooter with stat upgrades, evolving classes, and multiple modes. Where Agar.io had been about pure growth, Diep.io added build choices, role specialization, and competitive depth. It became the deepest .io game on the web and stayed that way for years.

3. Agar.io

Year two of Matheus Valadares’ founding .io title was still a strong year. Agar.io had been the breakout hit of 2015, and 2016’s audience extended that. The cell-eating loop — eat smaller cells, dodge bigger ones, grow toward the top of the leaderboard — kept new players coming in. Agar.io was no longer the only .io game on the block by mid-2016, but it was still the one most people had played first.

4. Mope.io

Stan Tatarnykov launched Mope.io in 2016. The animal-evolution survival game gave players a longer match arc than Slither or Agar — start as a small animal, eat to earn experience, evolve up the food chain, and eventually reach the dragon tier. The depth-of-progression element distinguished Mope from the pure-growth .io games and built a strong long-tail audience.

5. Cookie Clicker

Three years old in 2016, Cookie Clicker was still being actively updated by its creator, Orteil, with new buildings, upgrades, and prestige content arriving over its long life. The game had moved past its 2013 viral moment but had become the canonical incremental — the one people pointed to when explaining the genre.

6. A Dark Room

Doublespeak Games’ minimalist survival narrative was three years old in 2016 and kept finding new players. The slow reveal — one button, then ten, then a world, then a devastating ending — was impossible to spoil, which is why discovery kept happening years after launch.

7. Wings.io

The fighter-plane .io game launched in 2016 and built a solid player base. Top-down air-to-air dogfights with power-up pickups in a small arena. Wings.io was less famous than Slither or Diep but mechanically distinct enough to carve out its own audience.

8. The Chrome Dino game

The Chrome UX team’s offline endless runner (Sebastien Gabriel, Alan Bettes, and Edward Jung) was two years old in 2016 and built into Chrome. It may well have been one of the most-played browser games of the year by sheer reach — people hit it whenever their Wi-Fi blinked. A clean version of the T-Rex Runner runs on our homepage if you want to play without simulating a network outage.

9. QWOP (browser-playable)

Bennett Foddy’s deliberately punishing track-and-field game from 2008 stayed popular through 2016 in the browser. The Q-W-O-P keyboard control scheme — one key per leg muscle — made finishing a 100-meter race a genuine accomplishment. The game continued to inspire YouTube content years after launch.

10. Cubefield

Cubefield, a Flash cube-dodger usually dated to around 2006 and credited to Max Abernethy, was a decade old in 2016 and still a school-computer staple — a fixture of “unblocked games” lists. Pure reflex gameplay — steer a triangle through an endless field of cubes that gets progressively faster. Cubefield’s longevity is the kind of thing that happens when a game does one thing perfectly.

11. Town of Salem

BlankMediaGames’ social deduction MMO continued to grow through 2016. The 15-player role-based Mafia-Werewolf hybrid built one of the most engaged browser-game communities of the mid-2010s. Town of Salem, launched in 2014, predated the Among Us social-deduction boom by years.

12. Realm Grinder

Divine Games’ faction-based incremental had launched in 2015 and was mid-pack by 2016. The choice of good, evil, or neutral factions with branching mechanics gave the game a structural depth most clickers didn’t bother with.

13. Stick War 2

The Flash sequel to Max Games’ original Stick War (2009) was still widely played in 2016. Real-time strategy with stick-figure armies, multiple unit types, base-building. Stick War 2 was the genre’s accessible entry point — closer to a Flash classic than a 2016 release, but still pulling fresh players.

The Slither.io year

2016 was the year browser gaming proved it could produce hits at the scale of mobile blockbusters. A browser game sitting at number one on the App Store wasn’t normal — it was the browser briefly competing with mobile on equal terms. The game ran in any tab, no install required, with full multiplayer matchmaking that worked across continents.

The .io explosion that year — Slither in March, Diep in April, Mope and Wings later, and dozens of clones in between — set the template for the rest of the decade. Free-to-play, multiplayer-first, no install, two-minute sessions. Every browser-game studio after 2016 had to either compete with that template or work around it.

What didn’t make 2016 lists

Wordle (2021), Among Us (technically 2018 but didn’t blow up until 2020), and the post-2020 wave of NYT puzzle games didn’t exist in 2016. Universal Paperclips would arrive in October 2017. The defining hits of the late-2010s and early-2020s were still future games as of 2016.

Two 2016-style games on Dinogame

Neither of these is from 2016, but both play like that year. Snake Arena is a Slither.io-style survival round against AI snakes: grow by eating, cut rivals off so they crash, then eat the food they drop and climb the leaderboard. Our Cookie Clicker keeps the classic loop of clicking the giant cookie and buying generators that bake for you.

Frequently asked questions

When did Slither.io launch?

Slither.io launched on March 25, 2016, from developer Steve Howse. Its iOS version reached number one on the App Store’s most-downloaded list that year.

When did Diep.io launch?

Diep.io launched in the browser on April 16, 2016, developed by Matheus Valadares, who had previously created Agar.io. It became the deepest .io game on the web and remained popular for years.

What was the biggest browser game of 2016?

By downloads and active players, Slither.io was the year’s defining hit. By sheer reach, the Chrome Dino game was a contender, since it shipped inside Chrome. By depth of gameplay, Diep.io held the top slot.

Was Mope.io launched in 2016?

Yes. Stan Tatarnykov released Mope.io in 2016. The animal-evolution survival game added longer-arc progression to the .io formula and built a strong audience through the year.

Was Agar.io still popular in 2016?

Yes. A year after its 2015 launch, Agar.io still had a large daily audience. It was no longer the only .io game on the block but remained the genre’s flagship simple-and-accessible entry point.

The takeaway

2016 was the year the browser produced a hit at App Store scale. Slither.io did the improbable — a free browser game that topped the mobile download charts. Diep.io and Mope.io showed the genre had depth as well as reach. For an evergreen browser loop from the same era, the dino game at the top of this page is the quiet year-2016 standard that’s still running in 2026.

Related: Best Browser Games of 2018 (The .io Boom Year) · 12 Best .io Games to Play Free in Your Browser · Best Browser Games of 2025 (Year Retrospective)