Go to the game's page on the site for which you want to write a review and to the right there's an option to 'Write a Review'.
Amped 2 is accessible in the Cheats section of the site, so you can write a review for it. As long as a game is accessible somehow on this site (review, preview, cheats, etc.) you can write a review for it. Otherwise, you're out of luck.
I vote we add a new forum exclusively to allow creator the freedom and space to innovatively ask the same questions over and over again, all the while adamantly refusing to use the ENTIRE KNOWLEDGE OF THE HUMAN ENDEAVOUR AVAILABLE TO HIM BY VISITING A DIFFERENT SITE THAT ALSO STARTS WITH A "G".