Unfortunately it doesn't work for me :(

Why? does it not run?(is there an errer mesage?) or does the gampley suck?

Can't open the file sadly ):
(HP laptop win7)

it doesn't run dude.

Guys you nead java 8.

Sorry, no Java.

The text was hard to read, but the dimensional part is rather nice.

Okay... good job getting this done in 48 hours, but this game is difficult to play, and not in the good sense of difficulty. There are a lot of details that could be fixed to make the experience better:
* I never got the shooting part to work. I pointed and clicked, but no one ever seemed to get shot.
* The enemies don't despawn when you die, meaning that if you die by your checkpoint, they'll camp out and kill you again when you come back.
* It seems as if clicking the portal doesn't always teleport you, according to rules I don't understand. Is there a cooldown? If so, it should be clearly visible to the player how long they have to wait before they can switch dimensions again.
* I lose half my life if I fall further than 3-4 blocks. This feels a bit unfair - especially around the end when you pretty much have to take a fall of this height to proceed.
* A minor gripe, but the font is pretty hard to read.

If these things were looked at, I think your game could be a lot better. If something strikes you as a possible bug, I ran your game with the latest Java 8 on OS X.

how am I supposed to run this thing?

When doing community based competitions like Ludum Dare, it's in your best interest to make the game as easily playable by a lot of people as possible. Putting it in a .rar file is already going to turn away a lot of people. Requiring Java 8 is just another layer of difficulty.

Good job!