When I think about excellent but underrated games on the App Store, Marco Mazzoli's Spirit [99�/HD] immediately comes to mind as a prominent example. Launching back in February of last year, Spirit is a neo-retro arcade game that uses a control mechanic that's perfectly suited to the touch screen. You control your tiny "Spirit" with your finger, and as enemies appear on the screen they are dispatched by quickly circling your Spirit around them, creating a vortex that sucks them in.

Things get increasingly hectic as more enemies show up and you try to encircle them in a vortex without also running right into them. Ultra-responsive controls ensure that it's never the game's fault when things eventually go sour, and a nuanced scoring system adds layers of strategy to the gameplay. Last November a new Pulse mode was added into the game which basically turned the core game on its ear and offered a completely new way to play. It almost felt like Pulse could have been its own separate game rather than a free update to the existing Spirit app, but I didn't complain.

So, Spirit is pretty brilliant, and I like it quite a bit in case you couldn't tell. It's also been a well-supported game, receiving quite a few updates in the past year and a half since its release. However, one thing Spirit has been missing is high resolution visuals, and the colorful neon lines in the game look a bit jaggy on newer devices. Thankfully that problem has been rectified with the latest update to Spirit.

The developer has redrawn all the graphics in the game to utilize Retina Display and iPad resolutions. Like its classic arcade inspirations, Spirit has pretty minimalist visuals, but the extra fidelity of the high resolution art definitely makes a big difference. Aside from the visual improvements, this update also brings a slew of minor optimizations and tweaks, most notably better performance on older devices. Also, Spirit has a snazzy new icon.

If this is the first you're hearing of Spirit and you enjoy a good arcade-style high scoring game, then you should definitely give it a try. Both Spirit and the iPad native Spirit HD are currently on sale for just 99�, and are easily worth every penny. There is a dedicated group of players in our forums who would agree, and when it comes to original arcade experiences they don't get much better than Spirit.