You can play as China (multiple factions, IIRC) in
WinSPWWII from Shrapnel Games. (It's a modernized total conversion of the 90s classic
Steel Panthers - though the studio didn't buy the name, they bought the rights from the original creators and are the new publishers now.) The game covers a 1920s-1950s timeframe, so you won't have to play purely WWII-style engagements between armies.
I am not sure how the
Hearts of Iron games from Paradox Interactive handle interwar and WWII China. You'll be better off asking some board members who have played that series extensively.