Game needs to do a better job teaching you the mechanics. Maybe a clearer indication that the boss has changed, with different target points. The way I thought the game worked at first is that during reverse mode the boss's health also goes down, so you didn't want to catch your rockets unless they missed. This made things a lot harder because now you have to keep away from the safe spots you were previously using and added more obstacles. This could be an interesting change. Could let the player keep the rockets that drop so the number of previously fired rockets keeps growing until it's just a massive wall of rockets. Think there's a lot of stuff you can do here with a single timeline shmup.