Veloc-t in Space!

Posted in: Uncategorized | February 15, 2022 | No Comments

Quick note to start – if you want to keep up-to-date on the latest TestTubeGames goings-on – I’d suggest you keep an eye on my Twitter feed or join the Discord. This space will likely just be for larger announcements, at least for the moment.

As of December, it was 10 years since Velocity Raptor’s initial release. So to mark the occasion, I released a brand new relativistic toy: Veloc-t in Space!

Race through the solar system (and beyond) at nearly the speed of light. Along the way, get a close look at the length contraction and weird time-travel effects that special relativity brings. It is available to play for free here: play Veloc-t in Space.

If you’d like to take a trip down memory lane for Velocity Raptor, here’s a Twitter thread where I did some navel gazing about its past, present, and future.


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10 Year Anniversary

Posted in: Uncategorized | November 29, 2020 | No Comments

The original TTG homepage in 2010

It was ten years ago, on this day, that I first launched TestTubeGames. Assuming negligible time dilation. And that, to me, feels like the right time to take a look back. Try to remember some of the key events in the past decade.

2010 – the origins

In November 2010, I launched this site. It started with the first version of the Gravity Simulator… one of my very original projects. And to this day, still one of the most popular. There actually was another project of mine out by then, though: the Pocket Slide Rule app. (I guess that didn’t warrant a site launch.) At the time, I was still working a full time job – as an educator at a museum. And it was there, in fact, that I first got started building animations and simulations, to use in some of our museum programs.


In December of 2011, I released Velocity Raptor. It was my first game, and took me *years* to develop. So the release was a big event. For me, at least. The game would go on to win a science visualization award from the National Science Foundation. The response to Velocity Raptor (and the fact that even after building and releasing such a complex game, I didn’t want to tear my hair out) helped give me an early boost of confidence that, hey, maybe I should keep doing this.

Yes, Velocity Raptor has changed a lot over the years.


The release of Velocity Raptor the previous year led to the big event from this year: leaving my job, and doing game development full time. It was a big leap, but one I knew I wanted to do.

I got right to work, and built one of my speediest projects right out of the gate, releasing Agent Higgs in the middle of 2012. As fate would have it, releasing it just weeks before the discovery of the Higgs boson. The game even got mentioned… err, not by name, but still… in the New York Times. It was also the first time I was *selling* a game, instead of just releasing it for free. And, uh, that was quite a learning experience. Turns out it was hard, even then, to get many sales on the app store.

I had fun with the promo art for this one.


After Higgs, I floated around a bit trying to find my next project. There was the ill-fated Quantum Kitty, that never saw the light of day. And a few other small projects, many of which hit dead-ends.

This was the year I released the first version of The Fittest. I also created the TestTubeGames forums, which breathed a whole lotta fresh air into my work. And in June of that year, I started working with Unity. It was this game-building tool that I would use to create all my later work.

Run, little creatures!


I rebuilt my first project, the Gravity Simulator, in Unity, and released it in March. This was the start of selling things in places other than the app store. It was also the start of my iterative streak — where I, uh, tend to revisit old projects *a lot*.

In 2014, I also released the first version of Bond Breaker – a game built in collaboration with the CaSTL research group.

A screenshot of Bond Breaker in process


Early this year I joined the Indie Game Collective, a group of other independent developers that shared a co-working space. It has been an invaluable community.

Also this year, I got more into contract work, building the software for an exhibit at a local museum.

And, oh, also this year, I had a kid.

Baby’s first playtesting


I started dabbling in creating educational videos this year, starting with one about parallel wires.

TestTubeGames also went international this year, taking me to a science game conference in Paris.

I also learned that year how to give instructions for my games in French.

And then that year, I released the two games you see in the above conference photo. The Electric Shocktopus, and Bond Breaker 2.0.

Not a small year.

2017 – 2018

It was around this point that things took a turn for the contract-ual, and I sought out more client work. I did a couple years of work on a games project at Northeastern, and did a few projects for museum exhibits. Financial stability was the name of the game, here. (Figuratively)


It was around this time that I came back from contract-work-land. And, boy, does it show. I released a flurry of new little projects this year: Black Hole Launcher, Swing Explorer, Why do Astronauts Float.

And this was the year I launched my Discord. Just like the forums had years before, this was a huge boon to me. The community aspect has always been pretty central to TTG.

Ah, the first message, where it was just me talking to myself. Classic.


The first part of the year I spent hard at work on A Sailor’s Life for Me, yet another contract project for a local museum.

That wrapped right around the time, uh, the world got especially weird. There are some other highlights from this year, though.

Evolving Art! With the help of the folks in the Discord server, we voted some art through 100 generations, finally giving me this great piece of art to frame.

Velocity Raptor! I’ve been hard at work on a new version of Velocity Raptor — which has been scope creeped beyond all recognition. For instance:

Or running through the solar system, perhaps:

And then there’s Agent Higgs, which is going to be making a comeback, too:


Ha, this is a post about the past, not the future.

A big thanks to everyone who has been along with me for this journey. Every player, every commenter (well, some commenters), every member who joined the community here – those are the things that really keep me going. And here’s to ten more years of science games.


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Velocity Raptor Merch

Posted in: Uncategorized | August 31, 2019 | No Comments

Want to sport your love of relativistic dinosaurs, but aren’t quite ready to go all-in for a tattoo just yet?

May I suggest a nice enamel pin?


I put in an order of Velocity Raptor pins, and she looks great on my messenger bag.  If you’re interested in picking up one, too, you can go to our newly-created merch page.  And if you’ve got your own merch ideas, there’s a survey you can take, too.


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Why do astronauts float?

Posted in: Uncategorized | June 6, 2019 | 1 Comment

I released a new project – which hits on one of my favorite little quirks of science… and science teaching.

With a son who’s *super* into space and astronauts, the topic of them floating comes up a lot.  In books, in videos, in conversations.  And I always find it fascinating to read the ways people talk about this.

Because the reason is actually pretty weird.

And hard to describe concisely.

And I’m always interested to see whether the latest kids book we’re leafing through will (a) avoid the issue of ‘why’, (b) get it totally wrong, or (c) spend a weirdly long time technically trying to explain it.

Anyway… on to the main point here.  Why *do* astronauts float in space?  And how would you explain it to someone?

Here’s how *I* would, at least:


Astronaut floating over earth

So pop on over and check out my explainer / toy: “Why do astronauts float?


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Black Hole Launcher

Posted in: General News | April 11, 2019 | No Comments

With the release of the first picture of a black hole this week – I decided a new project was in order.  Gotta jump on the hype train, after all.

The only problem was I thought of this on Monday, and the picture was coming out Wednesday.

It was going to be a rush order.

I already had a fair bit of the tech in order, with my other General Relativistic projects, so it was doable.  And indeed it is done — Black Hole Launcher.

I figured I’d boil it all down to just throwing rocks around a black hole.  Simple to play around with for a few minutes, or longer if you got really into it.  Eventually scope-creep came in (just a bit!) and I added light beams, and a variable mass for the black hole, etc.  But it still stayed delightfully minimal.  (A new thing I’m striving for in my projects).

So go ahead, give it a try.  See if you can get a rock to orbit.  Can you detect any precession?  How about light beams, can they orbit?


Black Hole Launcher Screenshot


And a quick, more general note on TestTubeGames.  Right now, I’m exploring making smaller, quicker projects… so keep an eye on this space for new things.  I’ve also built a new Discord server for folks that want to chat a bit more and get an inside scoop, which you can find here.

Thanks for your support!


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Hollow Planets

Posted in: Gravity Simulator | October 1, 2018 | No Comments

I got a great question from someone who’d been using GSim – let’s call them B.A.

To paraphrase: can you make a ‘hollow’ planet in the simulator, and test out how gravity would work inside it.

This ended up being a more interesting challenge than I realized, so I figure I’d share my response with all of you:

Ah, good question – I had to think about that one a bit. The short answer is, yes.

Right now, if you have a single star and put an asteroid inside it… it will get absorbed. *But* if you place a static star, then put a *planet* inside it (while the collisions are turned off), then it won’t get absorbed, and it will move around affected by the gravity of the star.

In that case, though, the star isn’t treated as hollow, but instead as having a constant density. So just like if you drilled a hole all the way through the earth, where you’d fall down, feeling the varying effects of gravity as you did.

I don’t think that’s what you mean by hollow object, though. To create something truly hollow, which would have all its mass on an outer shell, we’ll have to get more creative.

At first I tried making a ring of smaller stars, to act like the outer shell of an object. The code is here:

//Gravity fun at TestTubeGames
_settings(gravity: r^-2);
_addCircle(vt: 0, r: 150, num: 400, col: 1, t: 0, m: 10, lcol: 0, noGrav);


Screen Shot 2018-10-01 at 10.39.48 AM

400 small static stars, arranged in a ring


If you try that, and throw in a few asteroids, you’ll notice that this doesn’t behave like you’d expect at all. Turns out, we made a flat ring, not a 3D shell, and they behave quite differently.

If you have the full version of the sim (the downloadable one), then you can set the simulation to be calculating in 2 dimensions, using the Physics menu, and that kind of helps — though introduces the issues that come along with calculating physics in different dimensions.


Then it struck me that a more straightforward(?) way to do this would be to create a star with negative mass… and put that *inside* the star with positive mass. (Negative mass is just a fun theoretical thing you can explore in the sim… but it’s very helpful here). If the two have the same density, then the negative mass and positive mass in any overlapping areas would cancel out to zero. With a slightly lower mass negative star overlapping a positive mass star, then, we can create a hollow object.

Here’s some code to try it out:

//Gravity fun at TestTubeGames
_settings(gravity: r^-2, x: 2.522413, y: 1.124918, zoom: 18.72843);
_add(m: 10000, col: 2, lcol: 3, pic: 0, noGrav, x: 0, y: 0);
_add(m: -9900, col: 16, lcol: 3, pic: 0, noGrav, x: 0, y: 0);


That thin yellow shell, if you can see it, is the surface of the hollow star.

That thin yellow shell, if you can see it, is the surface of the hollow star.


Make sure collisions are off, then fling some asteroids* in there. You should be good to go.

*due to an issue with the way density is calculated, stick with asteroids for this test for now. Planet behavior inside a hollow object is a bit broken.


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Feel Bad Friday: DF37

Posted in: Electric Shocktopus, Friday Fun | May 26, 2017 | No Comments

It’s been a bit quiet around here – I’ve cut down on my blog posts and twitter activity a bit.  *But* that doesn’t mean I won’t play a good ol’ Feel Bad Friday for you all!

NealCruco just shared DF37 in the forums with us, and this level does not disappoint.  Take a watch below.


Thanks to NealCruco for sharing the level!  To play this level (and more) you can check out the Level Creation Megathread in the forums.


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Gravity Simulator on Greenlight

Posted in: Gravity Simulator | December 8, 2016 | 1 Comment

After last week’s successful launch of The Electric Shocktopus (woo – it’s really out!), I’m wasting no time in getting my next game up there.

Gravity Simulator has always been a mainstay on this website – no matter what else I make, this project seems to dwarf the others in terms of traffic, eyeballs, engagement, and bug reports.  So let’s see what happens when we get this one in front of Steam!

First thing’s first, we’ve got to get this thing through Steam Greenlight:

GSim on Greenlight

Greenlight, for the uninitiated, is a system where people vote for whether or not games should get up on Steam.  Think Kickstarter, but where people just donate a vote instead of money.  Which is a horrible analogy.  (What next: “Twitter is like a cookbook where the recipes are people, and the ingredients are tweets.”)

Annnnyyyyway, keep your eye on this space for GSim hopefully following in Shocktopus’s tentaclesteps and making it way up on Steam soon.


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Shocktopus out on Steam!

Posted in: Electric Shocktopus | December 1, 2016 | 1 Comment

Well there ya go, it happened!  Shocktopus is up on Steam!

Screen Shot 2016-12-01 at 2.47.51 PM


You can check out the Steam page here, or see the (at the moment) quiet community page for the game here.  Ah.

If you’ve got the game already, through the Humble Widget, let me know and I can pass a Steam key along to you.

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A Shocktopus History – Part 4

Posted in: Electric Shocktopus | November 29, 2016 | No Comments

(The Electric Shocktopus is coming to Steam on November 30th (be there or be 1/r^2), so I figured it was a good time for a history lesson. To learn more, check out the first, second, or third parts of this series.)


It’s worth remembering that I didn’t start out to make a Steam game, or even a PC game.

Flashy Origins

When I started development on TES in 2013, my two platforms I’d built for were iOS (Agent Higgs, Slide Rule) and Flash (Velocity Raptor, Gravity Simulator).

After having just built an iPhone game, I wanted this next one to be web-based Flash game.  Web games are great!  They get a wider reach, hit more eyeballs, not to mention they are a better fit for a platformer – where you can use the arrow keys to run and jump around.

So that’s what I built.  And by February 2014, the Flash game was done.

The way money works in Flash games is through advertising and sponsorships.  You get a sponsor to pay you to have their name blasted on the front of your game, and then you get to give out the game for free.  Everyone wins.

I went to a match-making site for developers and sponsors, but I couldn’t find a sponsorship I liked.  I let the game sit on the auction site for months before deciding I needed to take another tack.

What went wrong with Flash?  Well, for one thing, the industry has had the rug pulled out from under it.  With the decline of Flash, there’s a lot less money to go around for Flash games.  My expectations may also just have been wrong – in retrospect, I don’t think the game was polished enough at the time.  And I think there’s something to be said for the niche nature of this game.  It’s a fun platformer, yes, but a big part of the allure of the game is the physics accuracy.  You are truly simulating electromagnetism in the game.  And for a sponsor who’s just looking for games, the fact this one is educational and scientifically accurate might not be a selling point at all.

What to do?

With Velocity Raptor – I simply released the game online, for free.  No sponsor.  No advertising.  I haven’t seen a penny off of it.  Which was fine, it was a labor of love I did while I still had a day job.  I just wanted to get my first game out there.  I couldn’t do the same thing again with The Electric Shocktopus.

But it took nearly a year to figure out what to do next.  In the meantime, I moved on to other projects.

Unity to the Rescue?

In November 2014, I announced that I was bringing Shocktopus to Unity.  It was time to leave the Flash world behind, once and for all.

Unity is a cross-platform game development tool, which means you can build a game in it, and export it to iOS, or web, or as a downloadable PC/Mac/Linux game, etc.  And it’s a whole lot more powerful than Flash.  I had been learning to user Unity in late 2013, and had been building Bond Breaker in it, and enjoying the results.  It was clear to me that Shocktopus’s future lay there, too.

The major reason, aside from ‘more power’?  I could easily make a standalone, non-web version of the game for players to download.  It could be bigger, badder, better, and something I could charge for, unlike a Flash game.  And I could still make a web version – a lite or demo version – if I wanted.

It wasn’t easy to switch over to Unity – it basically required a rebuild of the game.  But by February 2015, it was done.  I released the game publicly through a Humble Widget on my site.

It was technically in Beta mode, since I knew there were minor tweaks I’d like to do, but there it was.  I went back to working on other projects – and having a baby.

As a historical side-bar, I’ll note this is the time I started up the Feel Bad Friday videos, which have been going on (off and on) ever since.

Steam Greenlight

But selling it on my own site only gets me so far.  I knew I had to try to get the game up on Steam.  I prepared the materials, built a new trailer, and posted my Greenlight campaign in December 2015.  It got a nice flurry of feedback, which was very useful.  And then it quieted down.  And then I waited.  Again.

See a trend?  The Electric Shocktopus has had a fair bit of downtime.

But then, in August 2016 (what’s 8 months between friends?), I heard back that Shocktopus had made it through Greenlight!  Celebration ensued!

And also, questions.  What do I do now?  How do I release a game on Steam?  What are trading cards – and how do I make them?!

Steam Release

Which brings us to present day.  The game is getting released on Steam tomorrow, November 30, 2016, which Shocktopus gets released on Steam.  It’s been a long journey, years in the making, and while I’d be foolish to state it’s over, it feels like a nice goal for the game to have reached.

Until, that is, I make a VR version of it.

(Thus concludes the history lesson!  Here, have a cookie.)

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