Uh... well... this is a pretty good example of misleading marketing. How can using solo ships more fun than using full formation?
It's a short game with 3 stages that you can choose in any order. No final bosses. The ships you've chosen can't be chosen again in the run. That by itself is not a bad idea, but want a recipe for pain? Pick 3 ships at once and enjoy your hitbox becoming 3 times larger! Have I said that the ship is slow?
It's a shame that its flagship gimmick is just not fun because the unholy combination of fat hitbox and slow speed! A lot of the stage design demands tight maneuvers, at least when fighting the bosses. You'll struggle to survive at all because the ships can be all damaged at once in an uncontrollable barrage because you're using nerfed versions of the shots! Meanwhile when solo, where it is fun, the shots are strong and viable!
It's 6$, and I've played far worse shmups. This game, when played right, will provide you a decent time. The visuals and music are nice too.