I find so any useful resources linked to BBC KS2 Bitesize.  Their site is full of games and teaching tools for Language Arts, Math, and Science.  You may choose to select by subject or scroll through the “Find an Activity Here” section.

My years with intermediate students tell me that students will enjoy the game Viral Vinnie’s Gut Instinct.  Students choose the subject, enter their initials, customize their avatar, and choose their competitive mode. Teachers may create a League name that will enable up to 30 players to compete against each other.

This game is full of surprise “rewards”. Follow your own Gut Instinct and give it a try.