slimejs

Port of Slime Volleyball/Tennis/Cricket/Basketball to html5/javascript.

#Play it here #

What

Allows you to play the original "Slime" games as found on http://slimegames.eu/, http://slimetennis.com and other similar sites, without having to run Java in your browser.

How

This scrapes a few sites that still host the games as Java applets. It finds and downloads the .class and .jar files.

Once it has got all the compiled java classes, it uses fernflower to decompile them. This seems to have problems with renaming variables in subclasses, so there's also a custom IIdentifierRenamer to keep track of the renames and make regex bodging easier.

The java files then get transpiled using jsweet, after a lot of pre-processing, shimming and horrible regexes. They get transpiled to TypeScript, and I wrote TypeScript versions of all the Java dependencies that the games have (Applet, Image, System, etc.). There are a lot of assumptions made about the transpiler, the decompiler, and the original source code. The technique probably wouldn't immediately work for many other Applets if they were written in a different way.

In general, the original games work by liberally using Java's Thread.sleep and polling for game state. I shimmed this with a Promise wrapper for setTimeout, and made every method that called it async, and every method that called those methods, etc. So this may not work in browsers that don't like async/await.

The UI is rendered by calling equivalent html5 canvas methods from the TypeScript Applet shim. Some of them are still implemented a bit wrongly.

Why

I don't know.

Helping

If you want to work on this, I'll be... surprised.

You should be able to just clone and run npm install. This will take quite a long time because it gets dependencies from a few web services. The flow is more or less this:

You'll need Java 8 java and javac binaries on your system path.