In Nano Assault, you control a series of nanomachines as they are sent down to the surface of cells to destroy an incredibly dangerous virus that threatens the world. That's the extent of the story. For some this will be a massive disappointment, but it reminded me of a time when a game's plot was only there to set up the action and give you a reason to shoot things dead, rather than being the organic driving force behind your every action. You shoot things dead in increasingly elaborate and fun ways, which will be a nostalgic experience for many gamers who remember Asteroids.

There are three main objectives: destroy all of the viruses, find the missing data fragments, and survive. Most levels you will be doing all three, but some levels you just have to survive until the end and kill the elaborately designed boss. Some levels even require partial puzzle solving, and I admit I found the blend of different shooting styles and exploration elements to be a nice addition to the genre. That said, some of the levels have you searching around for that one final virus that's been evading you for what seems like an eternity. Not a huge problem, but it's definitely worth noting that it's bothersome, despite the built-in cell-map that's usually pretty good at helping you out.

The controls are simple enough. You use the analog nub to move and the lettered buttons to shoot in each respective direction. Pressing two adjacent buttons will cause you to shoot diagonally, giving you an 8-direction shooting range, which works very well. In addition to your basic pew-pew laser blast, you can also unlock and use various other special power-ups (one per level), such as homing torpedoes that hit multiple targets in sequence and powerful explosives. As the game progresses, the levels become increasingly elaborate and the volumes of enemies start to overwhelm, so it quickly gets complicated and ends up being very hectic fun.

Once I started playing, I couldn't stop until it was completed, which says all you need to know about how fun the game is... and its length. While the campaign has 32 levels, they go by very quickly and some of them can be completed in less than five minutes. Because of this I was able to beat the entire game in one sitting between lunch and dinner. I'm sad to say that, while the game was fun, it only lasted me three hours in total. If you take the time to fully explore all of the side content, you could extend that figure to five or six hours, but I doubt it would be much more than that. Once you've beaten the game you have the option to redo the levels with all of your power-ups for a leaderboard top score, time attack, or boss rush modes. I love that they included these extras, especially since the bosses were plentiful, varied, and very fun, but it's still just a case of repeating the story levels ad nauseum, so there's really no reason to return unless you absolutely adore the game. This is also the first game I've seen on the 3DS to utilize game coins, a platform-wide system of token use that encourages you to keep the system on you at all times in exchange for in-game bonuses and unlocks. I didn't use it very much, and I found you could get coins from doing the various game modes and time trials, but it's certainly a welcome addition.

 Of the 32 story levels, about a third of them are played in a completely different style from the usual top-down model. Instead, you head down a tunnel shooting at things in front of you. It's clear this set-up was developed to utilize the 3D effect because it's really hard to see what's coming when your ship is in the way. That said, the graphics and 3D effects are actually really good. Nano Assault has some crystal clear graphics and surprisingly unique art direction which really pops when add 3D effects to the mix. The audio, on the other hand, is completely forgettable, consisting of bland, generic techno tunes and boring, uninspired voice acting that could have been pumped out by a computer. 

The more I play shoot-em-up games, the more evident it is that they're meant to be replayed over and over again in search of top scores. Each is short, with a time trial mode and/or leaderboards, and Nano Assault is no exception. While the game looks and plays well, I still find it hard to recommend a game that can be so easily beaten in a matter of hours. Replay value is great but a game shouldn't rely as heavily on it as Nano Assault does. On the whole, it's a very enjoyable game, with great level design and graphics, hectic and fun gameplay, a fair difficulty curve, and smooth controls, but at the same time it's missing that certain something that would make it special.

This review is based on a 3DS retail copy of Nano Assault, provided by the publisher.