I don’t think that sounds like too much time at all. My 10 yr. old generally does 15-30 min. of math a day (at one time).
Don’t know if he’d like these games, but we have math bingo for add. and sub. facts—-I show the card (either add. or sub. side) and he has to guess the answer to know what # to cover. I can also play it making my older child multiply the facts (her answer isn’t correct, of course, just for practice!)
I haven’t tried math war, but think it would be fun. I believe you each lay down 2 cards and add/subtract/multiply them—whoever has the highest gets all the cards.
My daughter enjoys competition. We once did a contest with flashcards with her best friend. I held the card up, whoever got it first got the card. Winner got a prize (had one for both:) But maybe he could ‘race’ you.
Hope that helps some. Blessings, Gina