Sentence Ninja is easily and very customizable to fit most learner's needs. Used in conjunction with a therapist's clinical reasoning, it can be a powerful teaching tool. With 39 levels ranging from simple to complex phrases, syntax teaching can be fun and effective.
Using the Smarty Ears Therapy Report Center app, which I blogged about awhile back, the clinician or teacher can easily and quickly "dump" students into Sentence Ninja quickly. Data can be collected and shared as needed.
So, if you are working on Syntax, be sure to take a closer look at Sentence Ninja!