2010 and 2011 were the big years this week. In 2010, Valve took efforts to fix some problems with players bypassing restrictions on building construction and destruction using the console. Until now, Engineers could immediately destruct sapped buildings and spies could destroy their sappers, as encapsulated in this great video:
Fun fact: This happens because the game considers the sapper a building. This is why it’s immune to critical hits (a crit wrench does not remove it in one hit) and why the Homewrecker deals double damage to sappers (and does remove it in one hit)
In 2011 Valve added the adorable Itsy Bitsy Spyer and added crates 33 and 34, which I distinctly remember because 34 included the strange Amputator I wanted so badly. I remember buying a key immediately and giving it to the first person who handed me a strange Amputator, and then breaking it in on DeGrootKeep instead of writing my take-home midterm. Good times.