Colonel Levnekov said:
I only got the game recently, but what DLCs should I buy?
It feels pretty natural without any (playing vanilla base game right now).
Yeah, vanilla CK2 is perfectly playable. Your options are just limited to playing Christian Feudal Lords, but that was the original goal. There are also mechanics that are blocked, but the game is still playable.
As for what DLCs you should buy... Well, depends on what interests you I guess. Here is a basic review of the DLCs:
Expansions Packs
Sword of Islam : Unlock the possibility of playing a Muslim ruler.
Legacy of Rome: Adds Retinues, which is basically how the game represents the constitution of professionnal armies. Also add a lot of lavors to the Byzantine Empire (such as possibility of mending the schism and restoring the Roman Empire)
Sunset Invasion: Universally known as "that silly ASB Aztec Invasion". Basically has Aztecs invading Europe in the XIVth Century for the lulz. Since all DLCs can be activated/deactivated before launching the game, you can have it and still play historically by not activating it. But if you want to face a stupidly crazy but fun challenge of pushing back the Aztec Horde invasion as a Western European ruler once in a while, go for it.
The Republic: Unlock the possibility of playing Patricians and Merchant Republics.
The Old Gods: Adds a new start date in 867 and the possibility to play Pagans or Zoroastrians. Reworks the way revolts work and adds these interesting but annoying characters called adventurers.
Sons of Abraham: Adds Judaism to the list of playable religions. Adds also many flavour in regards to religion, but not the possibility of playing a theocracy.
Rajahs of India: Makes India playable. Also allows the possibility of adopting the local culture or religion.
Charlemagne: Adds a new start date in 769 and the possibility to play Zunists if you have The Old Gods. Also introduces custom Kingdoms and Empires as well as Viceroyalties.
Way of Life: Adds Focus, which basically adds more flavour events when playing a character. Fun and enjoyable but it's not exactly without flaws. Expects lots and lots of adultery because of seduction for example.
Horse Lords: Makes the possibility of playing Nomads available once activated and adds several other mechanics such as the Silk Road, Forts Tributaries and Raiding Adventurers.
The expansion packs are basically the "must go for" if you want to expand the game mechanics. That's your high priority target.
Customization Tools
Ruler Designer: Want to play as a famous wannabe that ended up conquering the world? This allows you to create a custom character by replacing a ruling character in the timeperiod you've chosen.
Customization Pack: Allows control on how every children of your dynasty is going to be called. Can also be used to rename realms and dynasties.
EU4 converter: Don't want the adventure to stop in 1453? Want to keep going on until 1821? If you own Europa Universalis IV, this little tool allows you to convert your CKII game into a custom EUIV start. Beware though as it is flawed.
These are basically only there if you want to play a custom games.
Musical and Graphical DLCs
That's basically all the Portraits Pack and "Songs of" DLCs. They basically do nothing but add new graphics and musics. They're very low priority and I would in fact say you can dispense from using them unless you are a completionnist like me.