I played all parts of ANNO. I like the fact it has a balanced economy and good war tactics. Other titles are too simple in economy or war or just too complex. The graphics are old school, but i like the simple style. Just need someone to play on LAN. :D Didn't experience any bugs so far.
Yes you have to type in a cd-key. But just use one from the internet. You can play with computers and your buddies on LAN(even with the same key!!) I like the fact you can concentrate on tactics instead of building factories, baracks etc. Normale you play 3-5 maps in a row. Because one match takes about 20-30 minutes. Great graphics, great gameplay. Would like to see a sequel!