So I am looking for any games that are relatively short to complete (Like 30 minutes or less, preferably less) that don't require me to pay and or download them. Any suggestions?

If you go to the games tab and open up the platform list, there's a Web option with tons of great browser games. I really recommend the Nitrome Series, Poptropica, and Endeavor.

Math vs monsters LUL

Oh, I didn't see the Web option lol. Thanks!