If you are looking for 5th grade interactive grammar games, you will find many online. Following are explanations of some of these sites and a summary of the instructions for playing the games.

If you had to pick just one site online to be your source of 5th grade interactive grammar games, Internet 4 Classrooms could be it. It has interactive games, quizzes, and activities in 10 grammar categories plus nine reading categories. Here is a breakdown of the number of activities in each grammar category:
As you can see, this site has a lot of different ways to improve grammar skills.
Grammar Gorillas is another fun grammar game with colorful graphics. Fifth graders would play the advanced level with all the parts of speech. There is an explanation and examples of a noun, verb, adjective, adverb, interjection, preposition, conjunction and pronoun on the page where the game is played. When your answer is wrong, the game explains why it is wrong. This is a very good game and should be very useful for students learning or reviewing the parts of speech.
Another of the 5th grade interactive grammar games online is Grammar Blast at Edu Place. The game is geared for grades 2-5. There are at least seven units on each level, and after two levels there is a review. Sentences, nouns, verbs, adverbs, adjectives, capitalization, prepositions, pronouns, and punctuation are all covered. Each level ends with a “Super Challenge Quiz on All Units.” You get two chances to get the right answer.
Teacher.Scholastic.com has five grammar games. These games cover subject-verb agreement, capital letters, punctuation, prefixes, suffixes, and homophones. The games have colorful graphics and are fun to play. One excellent game is an editing game called Edit Dan’s Copy. The higher of the two levels covers quotation marks, apostrophes, and run-on sentences. To play, you can either click the letters on the keyboard that is displayed in the game or you can type on your own keyboard. If you get the wrong answer, they display the right one.
The following sites have 5th grade interactive grammar games with more emphasis on words and making complete sentences. They include practice on synonyms, and antonyms, as well as some work on prefixes, suffixes, and punctuation.