When the PlayStation 4 launched last year, gamers were introduced to the little indie that could: Housemarque’s Resogun. Behind AAA titles like Killzone: Shadow Fall and third-party juggernauts like Assassin’s Creed IV: Black Flag, Resogun was a pure blast of arcade energy that took the best parts of classic Defender and improved upon them considerably. It did nothing new, but it was undeniably addictive. Now, seven months later, gamers are treated to the first paid DLC pack, following in the wake of the free update that offered a surprisingly robust ship editor and local co-op. Resogun Heroes attempts to bring some fresh ideas and welcome refinements to the already excellent Resogun formula, but at a full $5, are there enough?