Life & fun · alternatives · 2026

24 alternatives to Polygon Longform - Atlas Reactor

How an MMO studio created a great competitive game

Below are 24 products that do a similar job, ranked by how close each is in meaning and then by launch-day votes. Polygon Longform - Atlas Reactor launched in 2015; newer entries below may have overtaken it.

1. 1MI
   MMORPG in 55KB of Javascript▲178

   2013 · aberoth.com · its alternatives →

2. 2ES
   Eigengrau's Generator – A procedural city generator for tabletop gaming▲153

   2019 · github.com · its alternatives →

3. 3CA
   Crown – A flexible game engine written from scratch in C++▲193

   2017 · github.com · its alternatives →

4. 4AO
   An online 2D MMO game, written in Rust and JavaScript▲171

   I made a game (https://polyfight.io/) which revolves around a player (a tank) leveling up and upgrading by killing shapes and other tanks (partially inspired by https://diep.io). It has a bunch of features, a vast number of tanks, an inbuilt chatting system, clans to make teams with your friends, a colour scheme maker, controllable sandboxes which can be public or private, a last man standing gamemode, and an inbuilt 1v1 system with its own ELO rankings and a global leaderboard. The game has a few players right now, and I'd hope to spread the joy players have with…

   2024 · polyfight.io · its alternatives →

5. 5SA
   Strife, a 2D game library for Go▲85

   2018 · github.com · its alternatives →

6. 6TC
   The Choice – An online programming puzzle RPG▲95

   2013 · thechoice.amos.me · its alternatives →

7. 7
   Gridland ▲87

   An adictive roleplaying stacking puzzle

   2015 · its alternatives →

8. 8
   Rising World▲73

   A voxel based open-world sandbox game

   2015 · its alternatives →

9. 9AA
   Axis - a React.js multiplayer math game▲110

   2014 · axisthegame.com · its alternatives →

10. 10OR
    OpenRA – RTS project that recreates Command and Conquer games▲131

    2014 · openra.res0l.net · its alternatives →

11. 11SO
    Simple Open Source 3D Online Multiplayer Battle Game Using Node.js▲102

    2018 · paiza-battle-ground.paiza-user.cloud · its alternatives →

12. 12GO
    Gamification.org - Open Source Game Mechanics▲76

    2010 · gamification.org · its alternatives →

13. 13HM
    HTML5 MMORPG – almost 7 years in the making▲47

    2019 · data.mo.ee · its alternatives →

14. 14CT
    Crown – The Flexible Game Engine▲20

    2017 · github.com · its alternatives →

15. 15RA
    RIFT – A procedurally generated FPS game in the browser▲27

    2015 · team-duck.com · its alternatives →

16. 16BG
    Battleship game built with Elixir, Phoenix, React and Redux▲73

    2016 · github.com · its alternatives →

17. 17PP
    Practical, Pure Functional Game Engine▲29

    2014 · github.com · its alternatives →

18. 18
    Dawn of Steel▲62

    Mechanized RTS warfare and a race for dominance!

    2015 · its alternatives →

19. 19SA
    Skycraft, a creative voxel adventure game in WebGL▲23

    2013 · skycraft.io · its alternatives →

20. 20CA
    Cleven – a Common Lisp experimental volume graphics game engine▲37

    2015 · github.com · its alternatives →

21. 21SI
    Stomped.io – Massively Multiplayer HTML5 Platformer Game▲20

    2018 · stomped.io · its alternatives →

22. 22MT
    mgwuSDK, Turn Based Multiplayer SDK▲36

    2013 · makegameswith.us · its alternatives →

23. 23OS
    Open sourcing backend of our turn-based multiplayer gaming platform▲9

    2015 · bitbucket.org · its alternatives →

24. 24G
    gamedevwebtools▲35

    2013 · github.com · its alternatives →

Ranked by how close each launch is in meaning, then by votes. Prices were read from each product’s own site when checked and can change. Refine with your own description →