There is an independent game store on the far Northwest side of the Houston area, in Cypress.
If you go 290 outbound until you hit barker-cypress, go South down barker-cypress for a few miles and the store will be on your left. I don't know the exact address, but it is in a strip center near the Cy-fair college main campus. It is called GameShop, and the sign looks like a GameStop sign but it is not a GameStop.
Other than that I don't know of any, but Houston is big time underrepresented in the gaming world, especially compared to Dallas/Ft. Worth, or the even bigger "D" Denton. Not to say they are better cities, they are just better for gamers.
I am looking for a Wiimote though, I keep going to the TRU on Westiemer and the Targets/Walmarts along Westiemer and near the Galleria. I cannot find them in this town!!