Do you think I have to play Assassin's Creed to be able to understand and enjoy Assassin's Creed 2?

I'd suggest partial reading a summary of AC1 online. I didn't play AC1 sooner I got AC2. But basically...

So there's this guy named Desmond Miles, and he goes within a agent called an Animus which he exercising in substance to relive parts of his ancestors' nizzertit through their memories (Altair in AC1 and Ezio Auditore in AC2) to learn about the Templars. That's pretty much after what precedent the bifid tie in together. There is speculation that for AC3, you play as Desmond (which would be lame, a present zenith assassin? Thats what Splinter Cell and Hitman are beautiful much) but yea and he saves the world from 2012 (there's a wed 2012 references) apocalypse with the assassination techniques he's pluck up coming out of Ezio and Altair. That's partial what I've heard.