Can you end a sentence with an adjective? Example: Hey son, you played exceptional!
You can, but it isn't correct in this case.
It isn't incorrect to end a sentence with an adjective. For example, "My shirt is red." is a grammatically correct sentence, even though "red" is an adjective.
However, in this sentence, you should use "exceptionally," not "exceptional," because adjectives (such as "exceptional") describes nouns, while you're describing a verb (playing), so you should use the adverbial form of the adjective "exceptional."