If the official games are blocked, these alternatives offer very similar gameplay (fast-paced movement, killstreaks, and loadouts) and are often hosted on "unblocked" game sites: Combat Master

For basic URL filters, paste the address of the blocked gaming site into Google Translate. Set the source language to something other than English, and set the target language to English. Click the translated link generated in the right-hand box. Google will render the page within its own infrastructure, bypassing local URL restrictions. Tips for the Best Gaming Performance