How to make a game like CreepTD?

Hi guys, I'm actually planning to make an online multiplayer game like this, not with this tower defense style, but I want to make a website like this one where you can join or create a server.
Do you know how how can I do that?
and, do you know in what language is this game programmed?

[krunx]

The game is programmed in Java and commented in English.

For Websites you need HTML;

The game is programmed in Java and commented in English.

For Websites you need HTML;

And should I start programing the game in java for single player and then make it online and multiplayer?
or should I start doing the game online from the beginning?

[dcode]

I'd say this depends on the programming experience you already have. Do you have some experience in Java, Flash, .net or another language that would be suitable for this purpose?

I know the basics of Java, and this woud be a starting project

probably I should make the game totally on single player first, and then modify it
also, I don't know anything about html

[dcode]

If you don't have a lot of knowledge in network programming, this would be the best way to go, yes. Create a working single player game and later on extend it with multiplayer functionality.

I'll take your advice
Thanks a lot!