Welcome to this week’s first game-focused edition of iPhone + iPad Gems! Today, we’re looking at four titles—three different games, and one app that’s unusually designed to turn specific iPhones and iPads into accessories for an iOS or Mac game. Our top picks in this collection are iBlast Moki 2 HD and Cubes vs. Spheres, but Phoenix HD is also worth checking out as a free overhead shooter. Read on for all the details. Cubes…