chir.ag/stuff/sand

The Falling Sand game has been around for a while, and allows you to create paths, structures and flows from 4 falling sand elements. Simple, but oddly addictive.

http://chir.ag/stuff/sand/

madsmx.tripod.com/cannon.html

Cannon Defender is a classic "shoot stuff out of the sky" arcade game, implemented very nicely as a Java applet.

http://madsmx.tripod.com/cannon.html

www.mojang.com/notch/j4k/l4kd/

Left 4k Dead is an applet game written for a Java 4k coding challenge - it is inspired by the Left 4 Dead arcade game, but is implemented as a Java applet, in just 4k, which is a hell of an achievement. It's actually good fun to play.

http://www.mojang.com/notch/j4k/l4kd/

allstarpuzzles.com

This site has a collection of pen and paper puzzles, such as anagrams, Sudoku, and spot the difference (pictured), all implemented as Java applets.

http://allstarpuzzles.com/

www.interactivepulp.com/pulpcore/

PulpCore is a really impressive framework for creating Java applet games that use smooth and rich 2D animations. It's open source too. Try the Milpa game demo, I had to double check that it was really using Java, not Flash.

http://code.google.com/p/pulpcore/

http://www.interactivepulp.com/pulpcore/

www-jpc.physics.ox.ac.uk

JPC is an x86 PC emulator written as a Java applet. It's quite an impressive thing, having basically the same machine I had when I was growing up now running inside a web page. Plus, being able to play Prince of Persia doesn't hurt either...

http://www-jpc.physics.ox.ac.uk/

www.runescape.com

Well, despite the fact that we've had more than 3 kids in the house playing this against each other on several occasions, I didn't know that Runescape runs as a Java applet until Gary mentioned it last week.

For those that you that don't know, Runescape is a MMORPG (Massive Multiplayer Online Roleplaying Game) like World of Warcraft, which runs quickly and uses 3D graphics to display characters, locations and allow you to interact with other players anywhere in the world.

www.runescape.com

Super Mario Brothers

Not much of a business case for this applet, but it helps to demonstrate the wide variety of uses for Java applets: this is the Super Mario Brothers game in an applet.

http://www.nintendo8.com/game/629/super_mario_brothers/