Pixlgun 3D is a Minecraft-themed (though not affiliated with Mojang in any way) first-person shooter for both iOS and Android that recently updated with multiplayer, perhaps explaining its meteoric rise to No. 1 at the App Store (at the time of this review). But be warned that multiplayer is only offered over local Wi-Fi.
If you don't have friends sharing the same Wi-Fi, this means you'll be playing the campaign survival mode. In this mode you enter a series of levels where you'll need to kill every zombie on a map in order to move on to the next map. In the beginning, you start out on a small tutorial map (more on this later) with only a handgun and limited bullets, but as you play, you'll find more ammo and new weapons to help you in your mission.
Zombies and other enemies come in a variety of forms, mostly sticking to the Minecraft model, with slow walkers, cube-shaped slimes, and creatively designed Creepers. Though the monsters and maps are made out of blocks like they are in Minecraft, the graphics are very smooth and responsive as you play.
The problem with campaign mode is that it's always the same. You'll always start with the tutorial level no matter how many times you play, and you'll always see the maps in the same sequence. It would be better if you could choose to start on the second map, the graveyard, after your first run, but ideally, the game would also let you play through levels randomly as you go.
Still, the campaign mode in Pixlgun 3D is pretty fun, but it's far from being one of the top first-person shooters in the genre. The only reason I can see for its sudden rise on the Most Popular list is the addition of multiplayer, but, like I said before, you'll need to be near your opponents sharing the same Wi-Fi signal. The developers of Pixlgun say worldwide multiplayer will be coming soon, but as it is, getting all your friends together for a multiplayer game will likely be challenging.