Relativistic Asteroids is just Asteroids -- but with (some) relativistic effects added -- specifically, length contraction and time dilation.
As your ship accelerates, the little triangle that represents it visibly shortens (length contraction), and if you rotate, contraction is retained in the direction of motion, but not the others.
Time dilation isn't particularly notable--except that your bullets travel a shorter distance (when fired in the direction of motion), presumably because, in their frame they "expire" more quickly relative to the reference frame.
Pressing "f" during play shifts from the reference frame to the ship's frame, meaning that the ship looks normal, but now the asteroids are foreshortened in your direction of motion. (That's why the asteroids appear flattened in the screenshot above.)
This is actually kind of cute, and an imaginative way to demonstrate some of the physical implications of Einsteinian mechanics (though not necessarily to provide any real insight into why things happen as they do near lightspeed).
Some relativistic effects are not simulated -- and a shame that they aren't because they'd be interesting. There's no red or blue shift; asteroids are all Asteroids green, whereas in real life, objects moving toward you at relativistic speed appear bluer than they would at (relative) rest, and objects moving away are red-shifted. Implementing that strikes me as not all that difficult, and visually interesting.
Also, it does appear that only the player's ship is foreshortened by its velocity; while the asteroids don't accelerate, of course, it does appear that their shape is not affected by their velocity.
Finally, the notion of the light cone is not represented; by default, "light speed" in the game is 6 cm/sec, and the screen is considerably wider than that. This means that, say, when we view the screen from the ship's frame, and an asteroid is 6 cm away, we should see it at the position it occupied one second ago, not its current position. From all evidence, asteroids are drawn at their "real" positions, regardless of light speed.
Fun game to play? No, not really; it's just Asteroids with some interesting physical effects that, to the degree they affect gameplay, simply make it a big more frustrating. But it's an interesting use of gaming ideas to get across physical ideas -- and its only real flaw is that it doesn't go far enough to represent the effects of relativity.
I have long dreamed of
I have long dreamed of playing a game like this. I'm looking forward to having a free moment to find out how utterly unplayable it is :)
Time dilation isn't
Time dilation isn't particularly notable--except that your bullets travel a shorter distance (when fired in the direction of motion), presumably because, in their frame they "expire" more quickly relative to the reference frame.
That doesn't sound right; if a particle is moving near light-speed in a particular reference frame, it takes longer to decay than if it were at rest.
I can't play the game (no java), but I'd assume that the distance the bullet travels in its own frame is fixed, rather than the time it travels for. That would lead to the effect you describe.
Finally, the notion of the light cone is not represented; by default, "light speed" in the game is 6 cm/sec, and the screen is considerably wider than that. This means that, say, when we view the screen from the ship's frame, and an asteroid is 6 cm away, we should see it at the position it occupied one second ago, not its current position. From all evidence, asteroids are drawn at their "real" positions, regardless of light speed.
That's just how things are normally calculated in relativity: with regard to the reference frame itself, not an observer within it. We're seeing the position and shapes that truly exist in that reference frame, not the distortions introduced by POV. (If we truly were looking from the ships POV, you wouldn't see the far side of the asteroids, either in this or the regular game.)
While it would be interesting to include POV effects, I imagine it would a hell of a lot more complicated to calculate them.
One thing I'm curious about; what is the velocity of the bullets? Does the game handle the addition of velocities correctly?
It feels like there's
It feels like there's something a bit squirrely with respect to the size of the gameboard. I think the size of the gameboard is fixed within your reference frame, rather than in the stationary frame. Thus as length contracts, the fraction of the gameboard occupied by asteroids is reduced. This is visible in the screenshot for this article -- all the asteroids in a single band on the screen, when in the rest frame they would be evenly distributed.
Also, although the article header indicates that this is a Flash game, it actually seems to be Java.
Java
Sorry about that... Looks like Flash, and I have J2SE installed so I hardly noticed. But I've updated the header to say as much.
It's nice to see my game
It's nice to see my game reviewed on sites that I read. Thanks!
About the red/blue shift: Actually, we originally wanted to include those effects, but quickly realized that it would be incorrect. The light Doppler effect is a point of view relativistic effect, i.e., it's what you'd actually see if you were in the ship. However, as viewed from a co-moving reference frame as our game is, and with all asteroids moving in a transverse direction to the viewer (player) there is no shifting of the color. But people have made P.O.V. simulations which are pretty cool:
http://www.anu.edu.au/Physics/Savage/RTR/
I'd love to see someone build a relativistic FPS!
Time dilation: Not clearly evident in the relativistic classic Asteroid game we made, but if you play Nine 'Roid or the Sandbox, the asteroids blink and the time dilation is clear.
You were right about the playability...it's not so hot. ;) We just thought we'd finally carry out one of our "what if..." questions.
Sean
A Good Scenario for a Relativist 3D Game
...can be found in John Stith's Redshift Rendezvous, a science fiction novel that posits that inside a spaceship travelling through hyperspace, lightspeed is in the meters per second range, so that relativistic effects are visible to people in the ship.
just me?
When I tried playing this game, the applet would freeze when I started to accelerate. I had to restart Firefox because the thrust sound continued indefinitely. (I'm running Firefox 3.0b5 with sun-jdk-1.6.0.05.)