Welcome to this week’s unexpected second gaming edition of iPhone Gems! The release of four more interesting titles led us to put together an additional roundup of titles that are worthy of your attention, though three of the four should be pretty familiar to serious game fans: one is a clone of a classic Sega shooter, another duplicates popular action-puzzlers from Mitchell and PopCap, and a third borrows heavily from a 1980 Atari tank game.…