Been to over 30+ Rockets games this season. Paid exactly no money to park. The hell with paying in parking lots and garages. I park on the street parking meters. You don't pay after six pm, Monday through Saturday. This is what a parking meter in downtown Houston looks like. if you press the button to pay after six, it gives you a message. No, it doesn't say park for free, but it doesn't take money. It's free damnit. park on the street. The only time you can not park curbside on the street is when it is covered. You can't park there, park somewhere else where it is covered. I park off this square by Jefferson and Caroline. It's only a less than five minute walk. What I like best about curbside parking is that I don't wait to leave.
http://www.ridemetro.org/Services/Bus/Bikesonbuses.aspx or Free after 6pm and on Sundays **** paying money to sit in traffic.
My (no longer secret) secret is to circle around the Fullbright Tower or Houston Center. 9/10 there are multiple open spots on the street, some of it's metered, some not. If you do it right, no more than four blocks from TC. And one of the quickest escape routes, depending on where you're headed. Austin takes you away from the cluster**** after games.
Almost anywhere you start to see $5 parking, there usually is free parking on the side streets after 6pm. My go to spots are about 5-6 blocks away, but construction is killing alot of the better locations.