Stars are colossal fusion reactors, burning hydrogen into helium. As the nuclei fuse lighter elements into heavier elements, massive amounts of energy are released. A new game sets you the task of nucleosynthesis, building hydrogen into iron, and it's surprisingly fun.

At first glance, this game bears none of the hallmarks of fun for me. For all my scientific-giddiness, chemistry is the bane of my existence. Don't get me wrong — I love reading about it, and have a great deal of respect for those who make it work — but it's not something I do for fun. When diluting down HCl- for use in geology lab, I checked and double-checked with my friendly neighbourhood chemists that I had the right acid-to-water ratios to achieve the target concentration, and carefully follow instructions to add the acid to the water, not the other way around. Yet, as your dutiful Space Recruit, I took on the task of reviewing Fe[26], a new astronomy-themed game, just for you.

To my absolutely shock, somehow last night I misplaced an uncounted period of time to Fe[26]. The game is a stellar variant of 2048 (itself a variant of Threes), where you fuse elements together along the reaction pathways that power stars. I found myself sliding around tiles in an effort to get my star burning hydrogen into deuteron, cursing every time I accidentally paired Helium-3 with Helium-4 to get Beryllium-7 and needing to await its inevitable decay. Even when I reached the coveted Iron-26, I found myself wanting to keep playing, trying to get more blocks to mark this as an aged star. ...but then I took a wrong turn, accidentally boosting slowly-decaying Neon-20 into Magnesium-24 that I couldn't fuse into anything else, and soon it was all over with a star sputtering out on too many atomic dead-ends and nothing left to fuse.


Fusion in stars takes place in the high-pressure cores. Like in the game, hydrogen is in easy supply — even in an old, exhausted star has an outer shell of cool hydrogen. The creators have somewhat simplified the process to make it actually playable, but the pathways are accurate: hydrogen fuses into helium, helium ash can fuse into carbon and oxygen. This process releases even more energy, making the star burn brighter and increasing pressure in the core. The increased pressure allows more and more exotic fusion reactions in high-mass stars, fusing carbon into neon, neon into magnesium, or with ridiculously massive stars, oxygen into silicon. Each stage burns hotter, brighter, faster, running through fuel quicker so that while a star could fuse hydrogen for millions of years, it would run through neon in just one short year.

Eventually, the star is a layered onion, with lighter elements on the surface building to heavier elements in the core. When a real star fuses the game-winning Iron-26, the iron builds up in a dense core. No star is hot enough to fuse iron, so the intense pressure is no longer balanced by the heat of fusion. Electron degeneracy initially keeps the core from collapsing, but only for so long. Eventually, the core collapses catastrophically, failing in a fraction of a second in a supernova.


If you keep playing Fe[26] to build a core of iron, remember that you're courting disaster. Since I haven't had the patience to do that yet, make sure to take a screenshot for me documenting what, if anything, happens when too much iron builds up on the game grid. Just don't blame me if you find yourself in the middle of a cataclysmic stellar explosion as your computer goes supernova!

Images: Sun credit NASA/SDO. Game screenshot credit Fe[26]. Fusion diagrams credit Borb. Fore more science-based games, check out Stop Disasters! or the Kerbal Space Program.