There is an optional lock - on for targeting, but I wouldn't recommend it when using a weapon capable of hitting multiple enemies at once. (wccftech.com)
Even with multiple enemies on screen and interactive backgrounds, the game never misses a beat. (thedgcast.com)
The attacks you start out with will get you through each level fine but a few useful attacks, such as those which hit multiple enemies at once, should be obtained. (indiehangover.com)