Don't write this off as some minecraft spin-off. I'd say it's 5% minecraft, 95% Halo. Like I know a lot of people have probably said, it uses block-based maps, and if the host doesn't disable it, you can place and destroy blocks. But a large majority of the time, that's not the focus of the gameplay in the very least. It can be a pretty competitive FPS. Or it can just be a casual game to play with friends, if you're not the competitive type. There's your standard team death match mode, free for all, and capture the flag, which are the competitive modes. And then there's the more laid-back, casual modes in Zombie Survival and Infection. In Infection, all players start out as humans, with one randomly selected player as a zombie. If the zombie kills you, you respawn as a zombie, and the game is over when all the humans are dead. The winner is the player with the most kills. I don't really like it, because it seems like a boring camp-fest, and there's always that one guy that just digs a hole and hides with a shotgun. But overall, this game is really fun. If you like Halo, you'll like this.
The weapons are pretty standard. The sniper, battle rifle, pistol, shotgun, and machine gun are all straight out of Halo. There's also the energy sword, but it works a little differently in this. It doesn't instantly lunge and one-hit-kill like the Halo sword does, but instead has to be charged for 2-3 seconds. Or you can use two weak sword attacks instead. Then there's the hookshot. Basically, it's a grappling hook straight out of batman. Or the hookshot from Legend of Zelda, if you like. Then you've got your frag grenades, which can't kill a full health/shield player, and your plasma grenades, which only kill if you actually stick a player. Everything is pretty well-balanced overall.
In addition to standard fire modes, all weapons have a secondary function or alternate fire mode. The sniper/pistol/battle rifle have scopes. The shotgun camouflages you as the same kind of blocks surrounding you, and the machine gun empties the remainder of its clip at double the normal fire rate. The sword and hookshot don't have alternate fire modes.
Then, there's the miner gun. It can break single blocks, a 1x3 grid of blocks, or a 3x3 grid of blocks at a time. It also has a "Blaster" mode that requires time to charge, but releases a slow-moving explosive projectile. It can also be changed to "building" mode and used to place blocks, for mapmaking purposes, or building cover to hide behind.
Anyway, there's a lot of different things you can do in this game, and for $1.99, it's an investment you probably won't regret. If this sounds like something that would interest you, don't second-guess yourself. Buy it and come play with the rest of the community!