UPDATE:According to an user comment below in this page, Ace of Spades is no more free, it is now a commercial game. However there is a free version named Build and Shoot based on the same engine..
Here is the link to Build and Shoot
Ace of Spades is the best bits of Minecraft crossed with the fast-paced shooter gameplay of Team Fortress. Free and runs on any PC.
A nice neat 36Mb download, with 15 lovely little games included.
Download, Unzip, Play away!
Alien Deathmatch 2
Blockman Gets More
Greenie – The Eccentric Egyptologist
Greenie – The Helecopter Hero
Horizontal Shooter Redux
Mario’s Fiery Forth