http://ace-spades.com/

Ace of Spades is like a crossup betweeen Minecraft, and an FPS game. You play as either Green or Blue and the main objective is to capture the opposing team's intel. You can build bases, shoot people, dig massive tunnels. It's pretty addicting.

At this point, the game is only a week old. There aren't any admins or anything, so griefing is pretty rampant. There are also a lot of hackers (infinite health, infinite grenades and so on). They don't stop the game from being enjoyable however.

It's not hard guys.

Download it, install. When you click "Ace of Spades", it'll open the server list in your browser. Choose a server and you're good to go. You only have to open ports if you're hosting a server. If you join and there's a sea of grey, try a different server.