were developed, such as Globulation 2, which experiments with game management mechanics, the similarly experimental Liquid War, and the 3D projects 0 A.D. (a former freeware project), Boson, Battles of Antargis, Spring and Glest. Racing games, another uncommon Linux commercial genre, have also seen development. One of the earliest was RARS, which evolved following the principle of forking into TORCS and then Speed Dreams. MicroRacers and Toy Cars are inspired by Micro Machines, while Ultimate Stunts and Stunt Rally, are rooted in Stunts. Other racing games include versions of Racer, VDrift, Rigs of Rods, GLtron and Armagetron Advanced, YORG, the Mario Kart–inspired SuperTuxKart, Elasto Mania clone X-Moto, SkyRoads imitator Orbit-Hopper, sledding game Extreme Tux Racer, the text based ZRacer, and the top-down Trophy, Dust Racing 2D and Pixel Wheels. WorldForge, Ryzom, Crossfire, Solipsis, Illarion, and The Mana World are also examples of increasing diversification, offering free massively multiplayer online role-playing game worlds. Single-player role-playing games are also available, such as A Dark Room, Heroes of Allacrost, Valyria Tear, Empty Clip, Summoning Wars, GNU FreeDink, FLARE, Heroine Dusk, FreedroidRPG, the Cube World inspired Veloren, and the Pokémon derived Tuxemon, OPMon, and Pigeon Ascent. The rise of the independent game development in the 2000s and 2010s was partly driven by the growing ecosystem of open-source libraries and engines; indie developers utilized the open-source ecosystem due to good cross-platform capabilities and availability for limited financial burden. Game jams such as Ludum Dare and Game Off are also often run on open source principles, frequently using free frameworks such as pygame, LibGDX, Twine, Phaser, Cocos2d, Ren'Py and LÖVE. Educational languages such as Snap! and Scratch are also free software. Individual developers such as Jason Rohrer, creator of Passage and One Hour One Life, and Kenta Cho have also embraced open source. Greater organization Despite its initial roots as small private projects, the free software gaming scene has been becoming progressively more organized. The roots of this even go back as far as the games created for the GNU Project and to the original larger-scale free software projects like Freeciv. Still, for the most part free game development had very little organization throughout its history. Popular games were generally separate efforts, except for instances of people working on them known for other projects such as Ingo Ruhnke (Pingus), Bill Kendrick (SuperTux) and Steve Baker (TuxKart). Games were commonly found in directories such as The Linux