Best Browser Games of 2018 (The .io Boom Year)

2018 was the loudest year the .io genre ever had. Surviv.io, released in late 2017, hit its stride, Krunker.io launched, Hole.io went viral, and Paper.io 2 arrived as a sequel that landed harder than the original. The best browser games 2018 produced were, with a few notable exceptions, .io games — and the few that weren’t were sharing space with .io tabs on the same browser. Here’s the year that defined the format.

1. Surviv.io

Justin Kim and Nick Clark released Surviv.io in late 2017, but 2018 was the year it exploded. The top-down battle royale stripped PUBG down to a 2D map, no install, short matches. It was the right idea at the right time — every gamer in 2018 knew what a battle royale was, and Surviv.io let them play one in a tab. Smooth weapon balance and frequent updates carried it through the year. The original Surviv.io went offline in 2023; Survev.io is a community revival.

2. Krunker.io

Sidney de Vries launched Krunker.io as a browser open beta in 2018 (development later moved under Yendis Entertainment, and FRVR acquired the game in 2022), and it became the FPS that the browser had been waiting for. WebGL, blocky voxel-style art, no install, custom maps, a server browser. Ranked play and a competitive scene followed. Krunker proved the .io concept could scale to a real first-person shooter with competitive depth.

3. Hole.io

Voodoo’s Hole.io launched in 2018 on iOS and Android, with a web version alongside. The premise — control a hole that swallows everything it passes over, get bigger, swallow buildings — was peak hyper-casual, and it shot to the top of the free app charts. The browser version gave the same loop to anyone with a tab open, a good example of a mobile hit doubling as a browser game.

4. Paper.io 2

Voodoo’s sequel to the original Paper.io improved on the formula with new maps, special abilities, and tighter controls. The area-grab concept — claim territory by drawing closed loops, defend it from other players who can cut your line — worked even better in the sequel. For many players, Paper.io 2 quickly replaced the original as the version they opened.

5. Diep.io

Two years after launch, Diep.io was still the deepest .io game on the web. By 2018 the meta had stabilized — players had identified the strongest tank builds for each mode and the team-battle formats were the most active. Matheus Valadares had built a game that aged like a strategy classic, not a Flash fad.

6. Slither.io

Two years past its peak, Slither.io was still pulling big crowds in 2018. Steve Howse’s snake-MMO had become evergreen browser infrastructure. New players found it on every “best .io games” list; old players kept logging in.

7. Cookie Clicker

Five years old in 2018, Cookie Clicker was still being updated by Julien “Orteil” Thiennot, building on the big 2.0 overhaul of 2016 that added the dragon and expanded ascension. The game had transitioned from viral hit to cult standard, and it kept playing the same role for the rest of the decade.

8. Agar.io

Matheus Valadares’ original cell-eating .io game was three years old in 2018 and had settled into long-term maintenance mode. The game wasn’t growing, but it wasn’t shrinking either. Agar.io was the genre’s founding text, and people kept logging in for the same reason they kept loading the Chrome Dino game — instant access to a familiar loop.

9. Skribbl.io

The browser Pictionary-style game from developer ticedev launched in 2017 and spent 2018 growing into a go-to party game. Skribbl.io worked over a shared link, didn’t need accounts, and supported custom word lists, which made it an easy pick for friend groups, Discord servers, and office parties.

10. Universal Paperclips

Frank Lantz’s clicker about an AI making paperclips had launched in October 2017 and spent 2018 collecting recommendations. A full run takes a few hours, which made it a perfect “try this” share. It also kept appearing on best-of lists into 2018 — itself a sign of how few free browser games hit that quality bar in any given year.

11. Drift Hunters

The WebGL drifting game, released around 2017, spent 2018 taking over the “browser car games” category. Convincing drift handling, tunable cars, polished maps. It was the closest the browser had come to a proper driving game without an install.

12. Slope

Rob Kay’s Slope had been around since 2014, and by 2018 it was a Chromebook lunchroom staple. A ball rolls down an endless tunnel; you steer left and right and dodge obstacles. Pure reflex. The simplicity made it perfect for a quick round between classes.

13. Mope.io

The animal evolution survival game launched in October 2016 and had grown a real player base by 2018. Mope’s depth — eat smaller animals, evolve, gain new abilities, eventually become a dragon — gave players more reason to stay in a single match than most .io games.

14. Town of Salem

BlankMediaGames’ social deduction game had a strong year in 2018. Mafia-Werewolf hybrid with role-based gameplay, 15-player lobbies, a ranked competitive mode. It was the browser game closest in spirit to the Among Us boom that was about to start. Today it is mainly played through its Steam and mobile versions.

The .io year

2018 felt like the year .io games stopped being a curiosity and became a permanent fixture. Krunker.io, Hole.io, and Paper.io 2 all launched within the same twelve months, while Surviv.io and Skribbl.io from late 2017 hit their peak. The formula — free, browser-first, multiplayer, instant load — was the obvious solution to a market that increasingly didn’t want to install anything.

The boom also revealed the genre’s commercial problem. Most .io developers ran on display ads and optional cosmetic purchases, which capped studio revenue. Several of the biggest hits looked beyond the browser — Slither.io and Hole.io on mobile app stores, Krunker on Steam — to scale beyond what the browser ad model could support.

What didn’t survive 2018

Dozens of .io games launched in 2018 and died within months. The barrier to entry was low, but so was the audience patience for a game that didn’t immediately have full lobbies. The genre’s brutal Darwinism — a new .io game had to be playable, populated, and fun within ninety seconds of a first load — meant most attempts failed quietly. Even some of the year’s hits eventually disappeared: the original Surviv.io went offline in 2023.

Frequently asked questions

What was the biggest browser game of 2018?

Surviv.io and Krunker.io were the year’s two standout breakout hits. Among the older multiplayer games, Slither.io and Diep.io stayed among the most played through most of the year.

When did Surviv.io launch?

Surviv.io launched in late 2017 by Justin Kim and Nick Clark, but 2018 was the year it grew into a major hit and built its competitive community. The original version went offline in 2023.

When did Krunker.io launch?

Sidney de Vries released Krunker.io as a browser open beta in 2018. The WebGL-based browser FPS quickly developed ranked play and a serious competitive scene, and FRVR acquired it in 2022.

What was Hole.io?

Voodoo’s Hole.io is a hyper-casual game where you control a black hole that swallows objects to grow larger. It launched in 2018 on mobile, with a web version, and became a viral hit.

What was the difference between Paper.io and Paper.io 2?

Paper.io 2 added new map types, special abilities, smoother controls, and improved network synchronization. Many players quickly switched to the sequel.

The takeaway

2018 was the year the .io genre stopped being a wave and became a category. Krunker, Hole.io, and Paper.io 2 launched that year and are still around, even if Surviv.io’s original servers are not. For a different kind of browser staple from the same era — same browser, same no-install loop — the T-Rex Runner is the quiet evergreen that 2018 didn’t dethrone.

Related: Best Browser Games of 2016 (Slither.io Year) · What Is an .io Game? The Browser Game Boom Explained · 12 Best .io Games to Play Free in Your Browser