CAVE are among the best when it comes to the fairly niche bullet-hell shooter genre, and they've been pumping out hit after hit on consoles and in arcades for nearly two decades. They've also found great success porting their hit games to the iOS platform, where the top-down scrolling shooter has thrived making a transition to a button-less touchscreen. They've even released a couple of original mobile titles like Mushihimasama Bug Panic and Dodonpachi Maximum. Basically what i'm trying to say is that CAVE plus the mobile platform has brought forth many excellent games for us to play, and as a way to say thanks to all their fans the company is throwing a week-long sale on nearly all their iOS titles. Here's a full list.
If you're looking at this list and feeling lost as to which game or games you should be picking up, then definitely check out our reviews and the impressions in each game's forum thread, which should tell you pretty much anything you need to know. Also each one of these games has a lite version to try for free, for a hands-on feel of what you're getting. Honestly all of these games are easy recommendations for shooter fans, and my only real wish–barring Dodonpachi Maximum–is widescreen support for the iPhone 5. Maybe someday, eh CAVE? At any rate, all the sales above go all week long and into Sunday, so be sure to take advantage of the savings while you can.