I didn't play the game until a long time after I'd read the novel(s), and when I finally did it didn't really affect my interest in the novel, because there's really no overlap in characters/story-- the game follows one four-man squad, the novel follows a different one, there's some shared background (like the opening cutscene of the game) but other than that the novel really strikes out on its own.

If you haven't played the game, I highly recommend it! The opening cutscene is interactable, and follows the childhood/training of Boss, a Commando, from infancy through the first mission to Geonosis. It's honestly one of my favorite video game moments from ANYTHING.

Without spoiling anything, the RepCom game is one of those in which game mechanics enhance the story, especially in the opening tutorial mission and in the final mission of the game. The game has been on Steam for a long time and seems like it's always getting deep discounts, and it just recently got ported to Switch too!