2,000,000 systems played!

This week has been quite the ride. Super Planet Crash has been featured on io9, Huffington Post, space.com, Motherboard, and other online publications, and it “suffered” from repeated surges of traffic from imgur. Not bad for a game hacked together over the weekend! It overjoyed me to receive emails, and pictures!, by people enjoying the game, especially from the younger generation.

More than 2,000,000 games have been played as of today, and hopefully a fraction of those players will want to know more about exoplanets. I would also encourage everyone who enjoys this little free game to donate to science education funds, such as McDonald Observatory’s Science Education Fund. I would be oh so happy to have bragging rights due to planet crashers donating en masse!

I’m slowly trying to work through some of the feature requests. Not all are feasible on a short timescale (science is my full-time job, after all!), but I will strive to at least try to address the lowest-hanging fruit. One pet peeve shared by many was the inability to see the high-scoring games. In trying to address this, I discovered two bugs in the implementation of the high-scores.

The first is that the server relied too much on trusting the high-scores that were sent from the client (i.e. the Javascript running in the web-browser). Although I had tried to mitigate it somewhat, several fake high-scores were submitted. I added some stricter checks that should further help address the problem. The right solution would be to run the system on the server in order to check for any shenanigans. Unfortunately, this is unfeasible, as too many games are being played: it would place an unduly amount of stress on my server.

The second is a bug in the way systems were recorded and sent to the server. Some of the highest-scoring systems attempt to score high on masses, “crowdedness” (how close are the orbits of the bodies to each other) and habitability. They do that by (a) adding a binary companion (the “dwarf star”) and (b) putting a lot of planets in the same orbit within the habitable zone.

The resulting systems are likely highly chaotic, so any small error in recording the state of the system [ref]The state of the system being the current position and velocity of each body.[/ref] will change the outcome very quickly (the so-called “butterfly effect“). Unfortunately, one bug in Super Planet Crash resulted in this exact scenario happening. Any rounding or truncation of the floating point values for the coordinates will also affect the evolution of the system. The most common outcome is that these high-scoring systems will appear to be unstable when replayed. Grrr.

The decision I reached is to clean up the high-score table. The systems should now be recorded the correct way, and everyone will be able to see how the scores were achieved.

I understand this is sad news for the current record holders, so the screenshot at the top of this page will record the brave folks who reached upwards of 300,000,000 points for all posterity. (Just imagine someone unplugged the arcade machine by mistake…)

Next up on my agenda is releasing the game on GitHub. I am cleaning up the last few bits. If you are a programmer, you’ll be able to create pull requests for new features there.

In my next post, I will go into a bit more detail about how I created Super Planet Crash (and so can you!).