At first, you may think: well, this is just another Minecraft clone with guns, or even an Ace of Spades/Guncraft spin-off. In fact, it's something completely different, and I'm not talking only about the content it brings.
Blockstorm is a user content-driven multiplayer voxel shooter, with classic shooting mechanics, weapons, traps, explosives, tactical demolition and simple block physics. Pretty much any pattern you find in a First Person Shooter you'll also find here, what makes it distinct as a shooter, is the possibility to build and destroy, using your spade, explosives or bullets. And here you build for real, no pre-made constructs, just your creativity. Blockstorm is also a controlled shooter rather than an arcade/fast paced shooting hell: you can stop and think of your strategies instead of going rambo all the time. Destruction is also a powerful tactical weapon here: believe me, you won't like to be below a building about to collapse.
Content creation is also a plus: not only a powerful, fast and intuitive map editor lets you create and instantly share your maps with the community, but it will also let you design your own self in the game in character editor, with the same sharing ease. Content may be shared by files or just playing with someone who has the content. (There are some ideas to implement a weapon editor as well.)
But here is where Blockstorm gets the upper hand: a solid, friendly and oriented community. Devs and players stay every moment in touch, and the devs really listen to what players have to say. There have been two updates so far, which were results of suggestions and discussions, and as for the short period of time the game is online, it is improving on a regular basis. It shows great potential for the future, and I believe it will certainly be the best of its genre.
If you enjoy the classic voxel logic, customizing or making your own stuff, and First Person Shooters, give it a try, It's worth every penny.